# Category: GMAT Math

## 2018 GMAT Official Guide Bundle – Detailed Analysis

GMAT Genius has thoroughly analyzed the 2018 GMAT Official Guide Bundle and we want to share our insights with you. Feel free to read our detailed analysis of the 2018 GMAT Official Guide Bundle or skip down to our conclusions. Wishing you tremendous success with the GMAT!

## Overview of 2018 GMAT Official Guide Bundle

The Official Guides for GMAT Review contain retired real GMAT questions, and are an essential component of your GMAT preparations. The GMAC places questions in order of increasing difficulty, based on its assessment of difficulty. The three books in this bundle have no overlap in practice questions.

Our objective below is to provide a combined analysis of each question type (e.g. combine data for all Problem Solving questions across all books). You will find a list of new questions and detailed question categorization in our prior posts on the individual books:
The 2018 Official Guide for GMAT Review
The 2018 Official Guide for GMAT Quantitative Review
The 2018 Official Guide for GMAT Verbal Review

The 2018 GMAT Official Guide Bundle contains 220 new questions out of the 1,566 total questions (including Integrated Reasoning). Excluding the 100 questions in the Diagnostic Exam section of the main book, the new questions represent 15% new content. These are new questions that we have not encountered before; they are not questions recycled from older GMAC resources.

## Problem Solving

The 2018 GMAT Official Guide Bundle contains a total of 430 Problem Solving questions. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 185 43% +18
Medium 102 24% (5)
Hard 143 33% (13)

There are 61 new Problem Solving questions, with difficulty of Easy / Medium / Hard as follows: 37 / 12 / 12. This is in lieu of 61 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 19 / 17 / 25.

GMAT Genius classifies question difficulty into five categories. Our assessment of Problem Solving skews noticeably less difficult / more towards the center and is only 72.1% correlated with the GMAC’s assessment, demonstrating tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 44 10% +2
Easy 125 29% +2
Medium 166 39% (6)
Hard 68 16% (1)
Very Hard 27 6% +3

Although math questions often entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. We break down the 430 Problem Solving questions as follows:

Type Concept Number Percent Change
Arithmetic Basic 26 6% +5
Arithmetic Absolute Value 7 1.6%
Arithmetic Divisibility/Factors/Mult. 24 5.6% (1)
Arithmetic Exponents & Roots 26 6% (5)
Arithmetic Fractions & Ratios 50 11.6% (1)
Arithmetic Percents 32 7.4% (3)
Arithmetic Pos/Neg & Odd/Even 2 0.5% (2)
Arithmetic Primes 4 0.9%
Algebra Inequalities 9 2.1% +1
Algebra Linear Equations 23 5.3% +1
Algebra Simultaneous Equations 13 3%
Algebra Variables in Answers 13 3% +2
Geometry Circles 8 1.9% (1)
Geometry Coordinate 12 2.8% (1)
Geometry Rectangles 12 2.8%
Geometry Triangles 12 2.8% +2
Geometry Other 11 2.6%
Statistics Averages 32 7.4%
Statistics Other 10 2.3% +1
Word Problems Combinatorics 11 2.6%
Word Problems Functions & Sequences 22 5.1% (1)
Word Problems Groups/Sets 10 2.3% +1
Word Problems Probability 9 2.1% (1)
Word Problems Revenue/Profit/Interest 14 3.3% +2
Word Problems Rate & Work 20 4.7% (1)

## Data Sufficiency

The 2018 GMAT Official Guide Bundle contains a total of 322 Data Sufficiency questions. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 85 26% +9
Medium 90 28% +8
Hard 147 46% (17)

There are 45 new Data Sufficiency questions, with difficulty of Easy / Medium / Hard as follows: 13 / 16 / 16. This is in lieu of 45 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 4 / 8 / 33.

GMAT Genius classifies question difficulty into five categories. Our assessment skews significantly easier and is only 61.0% correlated with the GMAC’s assessment. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 21 7% +3
Easy 83 26% +5
Medium 144 45% (2)
Hard 62 19% (4)
Very Hard 12 4% (2)

Although many math questions entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. We break down the 322 Data Sufficiency questions as follows:

Type Concept Number Percent Change
Arithmetic Basic 20 6.2% +5
Arithmetic Absolute Value 1 0.3%
Arithmetic Divisibility/Factors/Mult. 17 5.3% +3
Arithmetic Exponents & Roots 26 8.1% (1)
Arithmetic Fractions & Ratios 19 5.9% (2)
Arithmetic Percents 21 6.5% (1)
Arithmetic Pos/Neg & Odd/Even 13 4% (1)
Arithmetic Primes 4 1.2% +1
Algebra Inequalities 26 8.1% +6
Algebra Linear Equations 14 4.3% +1
Algebra Simultaneous Equations 18 5.6% (6)
Geometry Circles 11 3.4% +1
Geometry Coordinate 11 3.4%
Geometry Rectangles 7 2.2%
Geometry Triangles 13 4%
Geometry Other 7 2.2% (1)
Statistics Averages 20 6.2%
Statistics Other 15 4.7% (1)
Word Problems Functions & Sequences 11 3.4% (1)
Word Problems Groups/Sets 15 4.7% +1
Word Problems Probability 4 1.2% (1)
Word Problems Revenue/Profit/Interest 8 2.5% (2)
Word Problems Rate & Work 11 3.4% (2)

## Sentence Correction

The 2018 GMAT Official Guide Bundle contains a total of 158 Sentence Correction questions. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 71 26% +5
Medium 75 28% (26)
Hard 125 46% +21

There are 38 new Sentence Correction questions, with difficulty of Easy / Medium / Hard as follows: 12 / 4 / 22. This is in lieu of 38 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 7 / 13 / 18. The GMAC has assigned a different difficulty rating to a total of 17 Sentence Correction questions, upgrading these 17 from Medium to Hard difficulty.

GMAT Genius classifies question difficulty into five categories. Our assessment skews noticeably easier and is only 59.9% correlated with the GMAC’s assessment, clearly demonstrating the subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 7 3% (1)
Easy 77 28% +3
Medium 110 41% (3)
Hard 65 24% +3
Very Hard 12 4% (2)

Although Sentence Correction questions typically entail multiple grammar concepts (as described on our website), GMAT Genius classifies questions based on our assessment of the primary tested concept. We classify the 271 Sentence Correction questions as follows:

Concept Number Percent Change
Verb Agreement 26 9.6% +1
Verb Tense 35 12.9% (1)
Pronoun Ambiguity 21 7.7% +2
Pronoun Agreement 15 5.5%
Parallel Construction 78 28.8% (6)
Misplaced Modifiers 33 12.2% +1
Idioms 19 7% +2
Comparison & Quantity 18 6.6% (1)
Expression & Meaning 26 9.6% +2

## Critical Reasoning

The 2018 GMAT Official Guide Bundle contains a total of 224 Critical Reasoning questions. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 72 32% (3)
Medium 71 32%
Hard 81 36% +3

There are 31 new Critical Reasoning questions, with difficulty of Easy / Medium / Hard as follows: 7 / 7 / 17. This is in lieu of 31 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 10 / 8 / 13. The GMAC has assigned a different difficulty rating to one Critical Reasoning question.

GMAT Genius classifies question difficulty into five categories. Our assessment skews slightly more towards the center, yet is only 72.3% correlated with the GMAC’s assessment, clearly indicating subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 1 0%
Easy 61 27% (8)
Medium 89 40% +1
Hard 52 23% +5
Very Hard 21 9% +2

We have grouped the questions based on the question type categorization that GMAT Genius uses for Critical Reasoning (as described on our website). We break down the 224 Critical Reasoning questions as follows:

Concept Number Percent Change
Weaken 49 21.9% +3
Strengthen 43 19.2% (3)
Assumption 22 9.8% +2
Reasoning 7 3.1% (1)
Conclusion 16 7.1%
Explain 23 10.3% (1)
Evaluate 22 9.8%
Boldface 13 5.8%
Complete the Passage 29 12.9%

The 2018 GMAT Official Guide Bundle contains a total of 261 Reading Comprehension questions across 52 passages. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 89 34% +10
Medium 101 39% (9)
Hard 71 27% (1)

There are 37 new Reading Comprehension questions, with difficulty of Easy / Medium / Hard as follows: 13 / 18 / 6. This is in lieu of 37 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 3 / 23 / 11. The GMAC has assigned a different difficulty rating to a total of 4 Reading Comprehension questions.

GMAT Genius classifies question difficulty into five categories. Whereas the GMAC assigns the same difficulty to all questions for a given passage (except in the Diagnostic Exam section), GMAT Genius assesses the difficulty of each question individually. Our assessment skews very slightly harder, but is only 58.8% correlated with the GMAC’s assessment, in large part due to different difficulty assessment methodologies. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 13 5% +1
Easy 65 25% +3
Medium 103 39% (3)
Hard 62 24%
Very Hard 18 7% (1)

We have grouped the questions based on the question type categorization that GMAT Genius uses for Reading Comprehension (as described on our website). We break down the 261 Reading Comprehension questions as follows:

Concept Number Percent Change
Primary Purpose 36 13.8% (2)
Author’s Tone 16 6.1%
Organization 8 3.1% +1
Function 35 13.4% +2
Specific Reference 62 23.8% (1)
Inference 87 33.3% (2)
Critical Reasoning 17 6.5% +2

## Integrated Reasoning

The main Official Guide (part of this bundle) includes online access to 58 Integrated Reasoning practice questions. The IR set includes 8 new questions that we have not seen before, plus all 50 questions from the prior 2017 edition. The 58 questions consist of the following four types:
Multi-Source Reasoning – 21 (3 new)
Table Analysis – 7 (1 new)
Graphics Interpretation – 12 (2 new)
Two-Part Analysis – 18 (2 new)

The GMAC classifies question difficulty into three categories of Easy / Medium / Hard as follows:
Multi-Source Reasoning – 6 / 7 / 8
Table Analysis – 3 / 1 / 3
Graphics Interpretation – 4 / 3 / 5
Two-Part Analysis – 5 / 7 / 6
Total – 18 / 18 / 22

Out of the 50 questions that carry over from the 2017 edition, the GMAC has reclassified the difficulty of 33 questions. For IR, GMAT Genius classifies question difficulty into the same three categories. Except for Two-Part Analysis, our assessment skews significantly easier, and contains notable differences from the GMAC. Our difficulty assessment is only 8.1% correlated with the GMAC’s assessment, clearly showing that there is tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown of Easy / Medium / Hard:
Multi-Source Reasoning – 9 / 11 / 1
Table Analysis – 3 / 4 / 0
Graphics Interpretation – 3 / 7 / 2
Two-Part Analysis – 2 / 10 / 6
Total – 17 / 32 / 9

## Online Interface

Each Official Guide book includes an access code (see inside front covers) that provides 12-month usage of an online version of the book. The online practice interface is the same as it was previously, except that the onerous limit of 10 saved sessions has been increased to 25 saved sessions in Exam Mode plus 25 saved sessions in Practice Mode (which you should not use, as mentioned below). The 100 questions from the Diagnostic Test chapter of the main Official Guide are available in a separate tab that works with Exam Mode functionality.

Since the GMAT is a computer-based test, we believe that it is advisable to work though the questions online. We strongly suggest that you use Exam Mode rather than Practice Mode, since we recommend that students practice using timed question sets that replicate test day conditions. The functionality of the online platform is good overall. You can choose practice sets by question type and difficulty level. Every question lists the corresponding book question number for easy cross-referencing.

## Other Notes

The Official Guides are for practicing with real GMAT questions, not for learning the underlying concepts. The 40-page Math Review section provides a very high-level overview of the math concepts tested on the GMAT. This math review will be highly inadequate except perhaps for the most advanced math students. Similarly, the brief introductions to the concepts tested on the verbal section are highly inadequate. We recommend that you use additional study materials to learn the math and verbal concepts.

Although all questions include answer explanations, many GMAT test takers are far from satisfied with these explanations. Math explanations can be brief and hard-to-understand for non-advanced students, and are sometimes convoluted or inefficient. Most GMAT test takers consider the Sentence Correction explanations quite cryptic. The Critical Reasoning and Reading Comprehension explanations, however, are reasonably good overall.

CONCLUSIONS

The Official Guide Bundle has three primary weaknesses, in our opinion:

1. An insufficient amount of difficult practice questions, particularly based on GMAT Genius’ assessment of difficulty. We are especially dismayed to see the net loss of 30 Hard-difficulty Quant questions (13 Problem Solving and 17 Data Sufficiency) based on GMAC’s difficulty assessment compared to the 2017 edition.
2. Math answer explanations that are too often either brief or convoluted and Sentence Correction explanations that are too cryptic.
3. Contrary to what the back covers of the books claim, questions are not fully presented in order of progressive difficulty for Reading Comprehension in the main OG, for Data Sufficiency in the Quant OG, and for Critical Reasoning and Sentence Correction in the Verbal OG.

Despite these flaws, the 2018 GMAT Official Guide Bundle is an essential source of GMAT practice. We believe that every GMAT aspirant must use all three Official Guide books (this or the prior edition). If you already have the 2017 editions of the Official Guides, however, the replacement of 106 math questions and 106 verbal questions is not sufficient to make this edition worth purchasing.

## 2018 GMAT Quant Official Guide – Detailed Analysis / Question Categorization

GMAT Genius has thoroughly analyzed the 2018 GMAT Quant Official Guide and we want to share our insights with you. Feel free to read our detailed analysis of the 2018 GMAT Quant Official Guide or skip down to our conclusions. Wishing you tremendous success with the GMAT!

## Overview of 2018 GMAT Quant Official Guide

The Official Guides for GMAT Review contain retired real GMAT questions, and are an essential component of your GMAT preparations. The GMAC places questions in order of increasing difficulty, based on its assessment of difficulty. The 2018 GMAT Quant Official Guide has no overlap with questions in the main Official Guide.

The 2018 GMAT Quant Official Guide contains 45 new questions out of the 300 total questions, representing 15% new content. These are new questions that we have not encountered before; they are not questions recycled from older GMAC resources.

## Problem Solving

The 2018 GMAT Quant Official Guide contains 176 Problem Solving questions. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 89 51% +4
Medium 43 24% (9)
Hard 44 25% +5

The Problem Solving section contains 26 new questions, with difficulty of Easy / Medium / Hard as follows: 15 / 5 / 6. This is in lieu of 26 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 11 / 14 / 1. Unlike in prior years, the GMAC has not reclassified the difficulty of any question.

GMAT Genius classifies question difficulty into five categories. Our assessment skews slightly more towards the center, but contains notable differences from the GMAC’s assessment. Our difficulty assessment is only 76.1% correlated with the GMAC’s assessment, demonstrating tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 21 12% (1)
Easy 55 31%
Medium 62 35% (1)
Hard 30 17% +1
Very Hard 8 5% +1

Although math questions often entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. We break down the 176 Problem Solving questions as follows:

Type Concept Number Percent Change
Arithmetic Basic 16 9.1% +2
Arithmetic Absolute Value 3 1.7%
Arithmetic Divisibility/Factors/Mult. 7 4% (3)
Arithmetic Exponents & Roots 8 4.5% (1)
Arithmetic Fractions & Ratios 22 12.5% +1
Arithmetic Percents 12 6.8% (3)
Arithmetic Pos/Neg & Odd/Even 1 0.6% (2)
Algebra Inequalities 4 2.3% +1
Algebra Linear Equations 9 5.1%
Algebra Simultaneous Equations 6 3.4%
Algebra Variables in Answers 5 2.8% +1
Geometry Circles 4 2.3%
Geometry Coordinate 5 2.8%
Geometry Rectangles 5 2.8%
Geometry Triangles 4 2.3%
Geometry Other 4 2.3%
Statistics Averages 14 8% +1
Statistics Other 3 1.7%
Word Problems Combinatorics 4 2.3%
Word Problems Functions & Sequences 12 6.8%
Word Problems Groups/Sets 3 1.7% +1
Word Problems Probability 2 1.1%
Word Problems Revenue/Profit/Interest 5 2.8% +1
Word Problems Rate & Work 8 4.5% (1)

Here’s a list of the 26 new Problem Solving questions:
13, 22, 29, 31, 52, 55, 65, 70, 71, 73, 74, 75, 78, 85, 89, 92, 99, 102, 104, 117, 135, 141, 144, 156, 165, 168

Here’s a list of the 176 Problem Solving questions categorized by primary math concept:

Type Concept Question #s
Arithmetic Basic 2, 5, 21, 44, 45, 67, 75, 77, 85, 88, 89, 92, 94, 100, 162, 170
Arithmetic Absolute Value 95, 105, 150
Arithmetic Divisibility/Factors/Mult. 52, 86, 103, 114, 122, 171, 173
Arithmetic Exponents & Roots 34, 36, 38, 48, 90, 112, 143, 160
Arithmetic Fractions & Ratios 8, 20, 24, 35, 40, 43, 46, 49, 54, 55, 60, 64, 73, 74, 78, 83, 84, 91, 108, 136, 144, 176
Arithmetic Percents 7, 17, 28, 30, 47, 59, 99, 111, 117, 118, 132, 168
Arithmetic Pos/Neg & Odd/Even 14
Algebra Inequalities 4, 29, 101, 163
Algebra Linear Equations 3, 9, 13, 15, 18, 42, 50, 71, 98
Algebra Quadratics 1, 19, 22, 33, 63, 66, 110, 121, 128, 156
Algebra Simultaneous Equations 12, 25, 31, 32, 41, 133
Algebra Variables in Answers 16, 39, 102, 120, 125
Geometry Circles 37, 134, 151, 169
Geometry Coordinate 26, 87, 96, 109, 115
Geometry Rectangles 11, 27, 104, 129, 175
Geometry Triangles 62, 68, 140, 164
Geometry Other 23, 139, 146, 149
Statistics Averages 10, 58, 61, 82, 93, 107, 119, 126, 131, 135, 147, 148, 153, 161
Statistics Other 72, 79, 81
Word Problems Combinatorics 152, 154, 155, 157
Word Problems Functions & Sequences 53, 56, 69, 76, 80, 116, 127, 137, 138, 145, 159, 166
Word Problems Groups/Sets 106, 141, 142
Word Problems Probability 158, 167
Word Problems Revenue/Profit/Interest 6, 65, 124, 165, 172
Word Problems Rate & Work 51, 57, 70, 97, 113, 123, 130, 174

## Data Sufficiency

The 2018 GMAT Quant Official Guide contains 124 Data Sufficiency questions. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 27 22% +1
Medium 33 27% +2
Hard 64 52% (3)

In the Data Sufficiency section, questions are not fully presented in order of progressive difficulty, contrary to what the back cover of the book claims. Based on difficulty levels provided in the online version, Medium and Hard difficulty questions are interspersed. The following table shows the question numbers for each difficulty level:

Difficulty Question #s
Easy 177-203
Medium 204-235, 239
Hard 236-238, 240-300

The Data Sufficiency section contains 19 new questions, with difficulty of Easy / Medium / Hard as follows: 2 / 6 / 11. This is in lieu of 19 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 1 / 4 / 14. The GMAC has not reclassified the difficulty of any question.

GMAT Genius classifies question difficulty into five categories. Our assessment skews significantly easier, and contains notable differences from the GMAC’s assessment. Our difficulty assessment is only 68.5% correlated with the GMAC’s assessment, demonstrating tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 12 10% +1
Easy 25 20% (3)
Medium 54 44%
Hard 27 22% +2
Very Hard 6 5%

Although many math questions entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. We break down the 124 Data Sufficiency questions as follows:

Type Concept Number Percent Change
Arithmetic Basic 3 2.4% (2)
Arithmetic Absolute Value 1 0.8%
Arithmetic Divisibility/Factors/Mult. 8 6.5% +2
Arithmetic Exponents & Roots 12 9.7% (1)
Arithmetic Fractions & Ratios 8 6.5%
Arithmetic Percents 6 4.8%
Arithmetic Pos/Neg & Odd/Even 5 4%
Arithmetic Primes 3 2.4% +1
Algebra Inequalities 12 9.7% +2
Algebra Linear Equations 3 2.4%
Algebra Simultaneous Equations 9 7.3% (5)
Geometry Circles 6 4.8% +1
Geometry Coordinate 4 3.2%
Geometry Rectangles 3 2.4%
Geometry Triangles 3 2.4%
Geometry Other 2 1.6%
Statistics Averages 6 4.8%
Statistics Other 5 4%
Word Problems Functions & Sequences 7 5.6%
Word Problems Groups/Sets 4 3.2% +1
Word Problems Probability 1 0.8% (1)
Word Problems Revenue/Profit/Interest 2 1.6%
Word Problems Rate & Work 4 3.2%

Here’s a list of the 19 new Data Sufficiency questions:
178, 193, 215, 216, 224, 226, 231, 239, 244, 246, 247, 257, 270, 281, 283, 285, 291, 295, 296

Here’s a list of the 124 Data Sufficiency questions categorized by primary math concept:

Type Concept Question #s
Arithmetic Basic 177, 180, 234
Arithmetic Absolute Value 214
Arithmetic Divisibility/Factors/Mult. 221, 224, 238, 247, 257, 272, 296, 297
Arithmetic Exponents & Roots 184, 210, 226, 240, 251, 254, 267, 268, 271, 282, 285, 300
Arithmetic Fractions & Ratios 182, 190, 201, 204, 233, 243, 255, 295
Arithmetic Percents 193, 199, 208, 222, 253, 266
Arithmetic Pos/Neg & Odd/Even 189, 196, 198, 213, 237
Arithmetic Primes 219, 270, 281
Algebra Inequalities 181, 188, 192, 200, 206, 215, 227, 231, 249, 252, 263, 276
Algebra Linear Equations 195, 218, 250
Algebra Quadratics 232, 239, 259, 265, 273, 279, 283
Algebra Simultaneous Equations 178, 202, 203, 217, 223, 230, 242, 269, 284
Geometry Circles 209, 216, 236, 256, 258, 278
Geometry Coordinate 191, 260, 290, 299
Geometry Rectangles 179, 185, 248
Geometry Triangles 261, 275, 291
Geometry Other 205, 207
Statistics Averages 194, 211, 228, 241, 244, 245
Statistics Other 225, 229, 235, 262, 294
Word Problems Functions & Sequences 197, 220, 264, 277, 280, 286, 287
Word Problems Groups/Sets 246, 274, 288, 293
Word Problems Probability 292
Word Problems Revenue/Profit/Interest 183, 186
Word Problems Rate & Work 187, 212, 289, 298

## Online Interface

The 2018 GMAT Quant Official Guide includes an access code (see inside front cover) that provides 12-month usage of an online version of this Official Guide. The online practice interface is the same as it was previously, except that the onerous limit of 10 saved sessions has been increased to 25 saved sessions in Exam Mode plus 25 saved sessions in Practice Mode (which you should not use, as mentioned below). The 100 questions from the Diagnostic Test chapter of the main Official Guide, but that are not contained in this printed book, are available in a separate tab that works with Exam Mode functionality.

Since the GMAT is a computer-based test, we believe that it is advisable to work though the questions online. We strongly suggest that you use Exam Mode rather than Practice Mode, since we recommend that students practice using timed question sets that replicate test day conditions. The functionality of the online platform is good overall. You can choose practice sets by question type and difficulty level. Every question lists the corresponding book question number for easy cross-referencing.

## Other Notes

The Official Guides are for practicing with real GMAT questions, not for learning the underlying concepts. The book contains a 40-page Math Review section that provides a very high-level overview of the math concepts tested on the GMAT. This math review will be highly inadequate except perhaps for the most advanced math students. We recommend that you use additional study materials to learn the math concepts.

Although all questions include answer explanations, many GMAT test takers are far from satisfied with these explanations. The explanations can be brief and hard-to-understand for non-advanced students. Furthermore, certain explanations are convoluted and overlook more efficient approaches.

## Conclusions

The 2018 GMAT Quant Official Guide has three primary weaknesses, in our opinion:

1. An insufficient amount of difficult practice questions, particularly based on GMAT Genius’ assessment of difficulty.
2. Math answer explanations that are too often either brief or convoluted.
3. In the Data Sufficiency section, questions are not fully presented in order of progressive difficulty, contrary to what the back cover of the book claims.

Despite these flaws, the 2018 GMAT Quant Official Guide is an essential source of GMAT practice. We believe that every GMAT aspirant must use this book (or the prior edition). For the best value, we recommend purchasing this book as part of the 2018 GMAT Official Guide Bundle. If you already have the 2017 edition of this book, however, the replacement of 45 questions is not sufficient to make this edition worth purchasing.

## 2018 GMAT Official Guide – Detailed Analysis / Question Categorization

GMAT Genius has thoroughly analyzed the 2018 GMAT Official Guide and we want to share our insights with you. Feel free to read our detailed analysis of the 2018 GMAT Official Guide or skip down to our conclusions. Wishing you tremendous success with the GMAT!

## Overview of 2018 GMAT Official Guide

The Official Guides for GMAT Review contain retired real GMAT questions, and are an essential component of your GMAT preparations. The GMAC places questions in order of increasing difficulty, based on its assessment of difficulty. This book has no overlap in practice questions with the Quant and Verbal Official Guides.

The 2018 GMAT Official Guide contains 130 new questions out of the 957 total questions (including Integrated Reasoning). Excluding the 100 questions in the Diagnostic Exam section of the book, the new questions represent just over 15% new content. These are new questions that we have not encountered before; they are not questions recycled from older GMAC resources.

## Problem Solving

The 2018 GMAT Official Guide contains 254 Problem Solving questions, including the 24 Problem Solving questions in the Diagnostic Exam portion of the book. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 96 38% +14
Medium 59 23% +4
Hard 99 39% (18)

The Problem Solving section contains 35 new questions, with difficulty of Easy / Medium / Hard as follows: 22 / 7 / 6. This is in lieu of 35 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 8 / 3 / 24. Unlike in prior years, the GMAC has not reclassified the difficulty of any question.

GMAT Genius classifies question difficulty into five categories. Our assessment of this section skews significantly easier, and contains notable differences from the GMAC’s assessment. Our difficulty assessment is only 69.9% correlated with the GMAC’s assessment, demonstrating tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 23 9% +3
Easy 70 28% +2
Medium 104 41% (5)
Hard 38 15% (2)
Very Hard 19 7% +2

Although math questions often entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. We break down the 254 Problem Solving questions as follows:

Type Concept Number Percent Change
Arithmetic Basic 10 3.9% +3
Arithmetic Absolute Value 4 1.6%
Arithmetic Divisibility/Factors/Mult. 17 6.7% +2
Arithmetic Exponents & Roots 18 7.1% (4)
Arithmetic Fractions & Ratios 28 11% (2)
Arithmetic Percents 20 7.9%
Arithmetic Pos/Neg & Odd/Even 1 0.4%
Arithmetic Primes 4 1.6%
Algebra Inequalities 5 2%
Algebra Linear Equations 14 5.5% +1
Algebra Simultaneous Equations 7 2.8%
Algebra Variables in Answers 8 3.1% +1
Geometry Circles 4 1.6% (1)
Geometry Coordinate 7 2.8% (1)
Geometry Rectangles 7 2.8%
Geometry Triangles 8 3.1% +2
Geometry Other 7 2.8%
Statistics Averages 18 7.1% (1)
Statistics Other 7 2.8% +1
Word Problems Combinatorics 7 2.8%
Word Problems Functions & Sequences 10 3.9% (1)
Word Problems Groups/Sets 7 2.8%
Word Problems Probability 7 2.8% (1)
Word Problems Revenue/Profit/Interest 9 3.5% +1
Word Problems Rate & Work 12 4.7%

Here’s a list of the 35 new Problem Solving questions:
3, 5, 6, 16, 22, 23, 24, 26, 33, 34, 40, 42, 50, 53, 55, 60, 68, 69, 72, 79, 81, 85, 90, 96, 98, 104, 122, 125, 139, 140, 151, 173, 201, 224, 229

Here’s a list of the 230 Problem Solving questions, excluding those in the Diagnostic Exam, categorized by primary math concept:

Type Concept Question #s
Arithmetic Basic 2, 19, 22, 37, 46, 79, 157, 173, 219
Arithmetic Absolute Value 25, 27, 65, 193
Arithmetic Divisibility/Factors/Mult. 33, 44, 54, 73, 81, 98, 121, 126, 136, 141, 154, 175, 176, 178, 195
Arithmetic Exponents & Roots 66, 68, 71, 74, 90, 92, 112, 147, 161, 180, 200, 209, 213, 216, 223, 230
Arithmetic Fractions & Ratios 3, 4, 5, 28, 30, 36, 45, 59, 63, 72, 75, 82, 91, 97, 103, 124, 131, 133, 135, 139, 160, 163, 189, 192, 203, 220, 222
Arithmetic Percents 1, 6, 10, 15, 55, 70, 80, 86, 87, 89, 94, 106, 108, 119, 122, 125, 153, 169, 172, 207
Arithmetic Pos/Neg & Odd/Even 62
Arithmetic Primes 181, 205
Algebra Inequalities 49, 78, 117, 185, 228
Algebra Linear Equations 7, 12, 31, 42, 53, 67, 83, 85, 109, 111, 128, 134, 179, 184
Algebra Quadratics 51, 93, 110, 127, 155, 168, 188, 226
Algebra Simultaneous Equations 13, 20, 35, 100, 150, 186
Algebra Variables in Answers 9, 16, 48, 57, 61, 144, 167, 190
Geometry Circles 95, 123, 146, 177
Geometry Coordinate 50, 56, 77, 101, 107, 183, 218
Geometry Rectangles 17, 18, 39, 58, 99, 156, 202
Geometry Triangles 26, 29, 43, 145, 174, 224
Geometry Other 32, 34, 114, 159
Statistics Averages 14, 21, 40, 41, 96, 116, 137, 138, 149, 158, 164, 171, 194, 211, 217, 227
Statistics Other 52, 84, 115, 151, 166, 197, 204
Word Problems Combinatorics 140, 148, 182, 187, 201, 214
Word Problems Functions & Sequences 47, 88, 104, 165, 196, 198, 206, 212, 225
Word Problems Groups/Sets 118, 120, 152, 208, 229
Word Problems Probability 11, 142, 162, 170, 221
Word Problems Revenue/Profit/Interest 24, 38, 60, 130, 143, 191, 210, 215
Word Problems Rate & Work 8, 23, 64, 69, 76, 102, 105, 113, 129, 132, 199

## Data Sufficiency

The 2018 GMAT Official Guide contains 198 Data Sufficiency questions, including the 24 Data Sufficiency questions in the Diagnostic Exam portion of the book. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 58 29% +8
Medium 57 29% +6
Hard 83 42% (14)

The Data Sufficiency section contains 26 new questions, with difficulty of Easy / Medium / Hard as follows: 11 / 10 / 5. This is in lieu of 26 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 3 / 4 / 19. The GMAC has not reclassified the difficulty of any question.

GMAT Genius classifies question difficulty into five categories. Our assessment skews significantly easier, and contains notable differences from the GMAC’s assessment. Our difficulty assessment is only 56.0% correlated with the GMAC’s assessment, demonstrating tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 9 5% +2
Easy 58 29% +8
Medium 90 45% (2)
Hard 35 18% (6)
Very Hard 6 3% (2)

Although many math questions entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. We break down the 198 Data Sufficiency questions as follows:

Type Concept Number Percent Change
Arithmetic Basic 17 8.6% +7
Arithmetic Divisibility/Factors/Mult. 9 4.5% +1
Arithmetic Exponents & Roots 14 7.1%
Arithmetic Fractions & Ratios 11 5.6% (2)
Arithmetic Percents 15 7.6% (1)
Arithmetic Pos/Neg & Odd/Even 8 4% (1)
Arithmetic Primes 1 0.5%
Algebra Inequalities 14 7.1% +4
Algebra Linear Equations 11 5.6% +1
Algebra Simultaneous Equations 9 4.5% (1)
Geometry Circles 5 2.5%
Geometry Coordinate 7 3.5%
Geometry Rectangles 4 2%
Geometry Triangles 10 5.1%
Geometry Other 5 2.5% (1)
Statistics Averages 14 7.1%
Statistics Other 10 5.1% (1)
Word Problems Functions & Sequences 4 2% (1)
Word Problems Groups/Sets 11 5.6%
Word Problems Probability 3 1.5%
Word Problems Revenue/Profit/Interest 6 3% (2)
Word Problems Rate & Work 7 3.5% (2)

Here’s a list of the 26 new Data Sufficiency questions:
233, 258, 260, 262, 266, 267, 273, 274, 276, 277, 278, 282, 284, 287, 288, 292, 293, 300, 306, 313, 326, 334, 339, 376, 382, 391

Here’s a list of the 174 Data Sufficiency questions, excluding those in the Diagnostic Exam, categorized by primary math concept:

Type Concept Question #s
Arithmetic Basic 258, 262, 270, 273, 283, 284, 288, 292, 309, 326, 329, 333, 334, 349, 372, 388, 403
Arithmetic Divisibility/Factors/Mult. 285, 293, 328, 337, 356, 390
Arithmetic Exponents & Roots 240, 243, 249, 281, 289, 330, 342, 350, 365, 370, 399
Arithmetic Fractions & Ratios 233, 256, 275, 312, 325, 335, 354, 368, 387, 402, 404
Arithmetic Percents 239, 253, 259, 269, 286, 313, 318, 319, 321, 324, 332, 340, 362, 397
Arithmetic Pos/Neg & Odd/Even 255, 271, 277, 278, 308, 314, 344
Arithmetic Primes 357
Algebra Inequalities 246, 274, 291, 306, 315, 320, 338, 355, 359, 361, 376, 391, 401
Algebra Linear Equations 234, 247, 252, 280, 290, 310, 339, 351, 352
Algebra Simultaneous Equations 232, 245, 303, 307, 322, 327, 345, 360
Geometry Circles 263, 287, 369, 379
Geometry Coordinate 235, 264, 331, 347, 382, 383
Geometry Rectangles 301, 311, 367
Geometry Triangles 231, 237, 260, 265, 346, 353, 384, 386, 398
Geometry Other 261, 304, 343, 371, 400
Statistics Averages 282, 295, 300, 348, 358, 363, 373, 375, 378, 381, 392, 396
Statistics Other 242, 244, 298, 317, 336, 385, 394, 395
Word Problems Functions & Sequences 241, 257, 364, 377
Word Problems Groups/Sets 248, 254, 266, 267, 276, 294, 305, 316, 389
Word Problems Probability 236, 297, 302
Word Problems Revenue/Profit/Interest 250, 268, 272, 296, 393
Word Problems Rate & Work 238, 251, 299, 341, 374, 380

## Sentence Correction

The 2018 GMAT Official Guide contains 158 Sentence Correction questions, including the 18 Sentence Correction questions in the Diagnostic Exam portion of the book. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 36 23% +1
Medium 49 31% (1)
Hard 73 46%

The Sentence Correction section contains 21 new questions, with difficulty of Easy / Medium / Hard as follows: 4 / 4 / 13. This is in lieu of 21 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 3 / 5 / 13. The GMAC has not reclassified the difficulty of any question.

GMAT Genius classifies question difficulty into five categories. Our assessment skews noticeably easier, and contains notable differences from the GMAC. Our difficulty assessment is only 56.8% correlated with the GMAC’s assessment, clearly showing that there is subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 3 2%
Easy 43 27% (1)
Medium 67 42% (3)
Hard 38 24% +4
Very Hard 7 4%

Although Sentence Correction questions typically entail multiple grammar concepts (as described on our website), GMAT Genius classifies questions based on our assessment of the primary tested concept. We classify the 158 Sentence Correction questions as follows:

Concept Number Percent Change
Verb Agreement 19 12% +1
Verb Tense 22 13.9%
Pronoun Ambiguity 12 7.6% +2
Pronoun Agreement 4 2.5%
Parallel Construction 50 31.6% (2)
Misplaced Modifiers 16 10.1% (1)
Idioms 8 5.1% +1
Comparison & Quantity 10 6.3% (1)
Expression & Meaning 17 10.8%

Here’s a list of the 21 new Sentence Correction questions:
674, 680, 684, 685, 699, 702, 717, 735, 743, 745, 750, 751, 763, 770, 777, 780, 781, 782, 784, 796, 799

Here’s a list of the 140 Sentence Correction questions, excluding those in the Diagnostic Exam, categorized by primary grammar concept:

Concept Question #s
Verb Agreement 670, 677, 685, 693, 707, 711, 721, 752, 753, 759, 771, 789, 792, 793, 799, 801, 807
Verb Tense 668, 686, 694, 701, 702, 708, 712, 722, 724, 731, 735, 740, 749, 754, 756, 764, 773, 781, 803, 804
Pronoun Ambiguity 671, 719, 743, 774, 775, 777, 778, 779
Pronoun Agreement 688, 738, 762, 765
Parallel Construction 669, 679, 680, 682, 687, 689, 692, 697, 699, 703, 710, 713, 714, 715, 725, 727, 728, 730, 732, 734, 736, 737, 741, 742, 744, 751, 755, 757, 760, 761, 763, 766, 767, 776, 780, 782, 783, 784, 794, 800, 802, 806
Misplaced Modifiers 683, 705, 706, 709, 716, 718, 723, 729, 739, 746, 748, 770, 790, 797, 798
Idioms 672, 695, 698, 717, 788, 795, 796
Comparison & Quantity 676, 678, 691, 704, 745, 758, 769, 772, 791, 805
Expression & Meaning 673, 674, 675, 681, 684, 690, 696, 700, 720, 726, 733, 747, 750, 768, 785, 786, 787

## Critical Reasoning

The 2018 GMAT Official Guide contains 141 Critical Reasoning questions, including the 17 Critical Reasoning questions in the Diagnostic Exam portion of the book. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 41 29%
Medium 44 31% (1)
Hard 56 40% +1

The Critical Reasoning section contains 19 new questions, with difficulty of Easy / Medium / Hard as follows: 6 / 2 / 11. This is in lieu of 19 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 6 / 3 / 10. The GMAC has not reclassified the difficulty of any question.

GMAT Genius classifies question difficulty into five categories. Our assessment skews slightly easier, but contains notable differences from the GMAC. Our difficulty assessment is 74.1% correlated with the GMAC’s assessment, clearly indicating subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 0 0%
Easy 43 30% (2)
Medium 49 35% (1)
Hard 36 26% +3
Very Hard 13 9%

We have grouped the questions based on the question type categorization that GMAT Genius uses for Critical Reasoning (as described on our website). We break down the 141 Critical Reasoning questions as follows:

Concept Number Percent Change
Weaken 29 20.6% +2
Strengthen 27 19.1% (2)
Assumption 15 10.6% +1
Reasoning 4 2.8% (1)
Conclusion 9 6.4%
Explain 18 12.8% +1
Evaluate 15 10.6% (1)
Boldface 9 6.4%
Complete the Passage 15 10.6%

Here’s a list of the 19 new Critical Reasoning questions:
546, 550, 554, 556, 561, 575, 589, 599, 626, 627, 631, 634, 635, 640, 643, 651, 656, 660, 661

Here’s a list of the 124 Critical Reasoning questions, excluding those in the Diagnostic Exam, categorized by CR question type:

Concept Question #s
Weaken 546, 549, 574, 575, 583, 588, 600, 606, 615, 617, 619, 620, 622, 625, 627, 629, 642, 646, 654, 658, 664, 666, 667
Strengthen 545, 547, 548, 552, 562, 566, 569, 570, 572, 576, 589, 592, 594, 595, 597, 598, 602, 604, 610, 611, 624, 631, 641, 648, 649
Assumption 555, 580, 584, 590, 607, 608, 614, 628, 635, 637, 645, 650, 655, 657
Reasoning 560, 567, 578, 633
Conclusion 544, 581, 591, 618, 634, 653, 662
Explain 551, 553, 556, 557, 558, 568, 586, 596, 613, 616, 621, 630, 640, 656, 660, 665
Evaluate 554, 559, 571, 573, 579, 585, 632, 636, 638, 643, 644, 663
Boldface 561, 565, 599, 623, 639, 647, 651, 652, 659
Complete the Passage 550, 563, 564, 577, 582, 587, 593, 601, 603, 605, 609, 612, 626, 661

The 2018 GMAT Official Guide contains 156 Reading Comprehension questions across 33 passages, including the 17 Reading Comprehension questions in 3 passages in the Diagnostic Exam portion of the book. The GMAC classifies question difficulty into three categories as follows:

Difficulty Number Percent Change
Easy 55 35% +4
Medium 74 47% +1
Hard 27 17% (5)

In the Reading Comprehension section, questions are not fully presented in order of progressive difficulty, contrary to what the back cover of the book claims. Based on difficulty levels provided in the online version, Easy, Medium, and Hard difficulty questions are interspersed. The following table shows the question numbers for each difficulty level:

Difficulty Question #s
Easy 405-438, 442-455
Medium 439-441, 456-516, 537-540
Hard 517-536, 541-543

The Reading Comprehension section contains 21 new questions in 6 passages, with difficulty of Easy / Medium / Hard as follows: 7 / 14 / 0. This is in lieu of 21 questions in 4 passages from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 3 / 13 / 5. The GMAC has not reclassified the difficulty of any question.

GMAT Genius classifies question difficulty into five categories. Whereas the GMAC assigns the same difficulty to all questions for a given passage (except in the Diagnostic Exam section), GMAT Genius assesses the difficulty of each question individually. Our assessment skews slightly harder, but contains notable differences from the GMAC. Our difficulty assessment is only 57.6% correlated with the GMAC’s assessment, in large part due to different difficulty assessment methodologies. Here’s our breakdown:

Difficulty Number Percent Change
Super Easy 7 4% +1
Easy 33 21%
Medium 65 42% (2)
Hard 41 26% +1
Very Hard 10 6%

We have grouped the questions based on the question type categorization that GMAT Genius uses for Reading Comprehension (as described on our website). We break down the 156 Reading Comprehension questions as follows:

Concept Number Percent Change
Primary Purpose 22 14.1% (2)
Author’s Tone 10 6.4%
Organization 5 3.2% +1
Function 20 12.8% +2
Specific Reference 38 24.4%
Inference 47 30.1% (3)
Critical Reasoning 14 9% +2

Here’s a list of the 21 new Reading Comprehension questions: 412 to 418, 439 to 441, 467 to 470, 514 to 516, 537 to 540

We have not provided a list of Reading Comprehension questions by category because it makes sense to practice on one passage at a time, rather than attempting all the Primary Purpose questions (for example) at one go.

## Integrated Reasoning

The 2018 GMAT Official Guide includes online access to 58 Integrated Reasoning practice questions. The IR set includes 8 new questions that we have not seen before, plus all 50 questions from the prior 2017 edition. The 58 questions consist of the following four types:
Multi-Source Reasoning – 21 (3 new)
Table Analysis – 7 (1 new)
Graphics Interpretation – 12 (2 new)
Two-Part Analysis – 18 (2 new)

The GMAC classifies question difficulty into three categories of Easy / Medium / Hard as follows:
Multi-Source Reasoning – 6 / 7 / 8
Table Analysis – 3 / 1 / 3
Graphics Interpretation – 4 / 3 / 5
Two-Part Analysis – 5 / 7 / 6
Total – 18 / 18 / 22

Out of the 50 questions that carry over from the 2017 edition, the GMAC has reclassified the difficulty of 33 questions. For IR, GMAT Genius classifies question difficulty into the same three categories. Except for Two-Part Analysis, our assessment skews significantly easier, and contains notable differences from the GMAC. Our difficulty assessment is only 8.1% correlated with the GMAC’s assessment, clearly showing that there is tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown of Easy / Medium / Hard:
Multi-Source Reasoning – 9 / 11 / 1
Table Analysis – 3 / 4 / 0
Graphics Interpretation – 3 / 7 / 2
Two-Part Analysis – 2 / 10 / 6
Total – 17 / 32 / 9

## Online Interface

The 2018 GMAT Official Guide includes an access code (see inside front cover) that provides 12-month usage of an online version of this Official Guide. The online practice interface is the same as it was previously, except that the onerous limit of 10 saved sessions has been increased to 25 saved sessions in Exam Mode plus 25 saved sessions in Practice Mode (which you should not use, as mentioned below). The 100 questions from the Diagnostic Test chapter are available in a separate tab that works with Exam Mode functionality.

Since the GMAT is a computer-based test, we believe that it is advisable to work though the questions online. We strongly suggest that you use Exam Mode rather than Practice Mode, since we recommend that students practice using timed question sets that replicate test day conditions. The functionality of the online platform is good overall. You can choose practice sets by question type and difficulty level. Every question lists the corresponding book question number for easy cross-referencing.

## Other Notes

The Official Guides are for practicing with real GMAT questions, not for learning the underlying concepts. The book contains a 40-page Math Review section that provides a very high-level overview of the math concepts tested on the GMAT. This math review will be highly inadequate except perhaps for the most advanced math students. Similarly, the brief introductions to the concepts tested on the verbal section are highly inadequate. We recommend that you use additional study materials to learn the math and verbal concepts.

Although all questions include answer explanations, many GMAT test takers are far from satisfied with these explanations. Math explanations can be brief and hard-to-understand for non-advanced students, and are sometimes convoluted or inefficient. Most GMAT test takers consider the Sentence Correction explanations quite cryptic. The Critical Reasoning and Reading Comprehension explanations, however, are reasonably good overall.

## Conclusions

The 2018 GMAT Official Guide has three primary weaknesses, in our opinion:

1. An insufficient amount of difficult practice questions, particularly based on GMAT Genius’ assessment of difficulty. We are especially dismayed to see the net loss of 32 Hard-difficulty Quant questions (18 Problem Solving and 14 Data Sufficiency) based on GMAC’s difficulty assessment compared to the 2017 edition.
2. Math answer explanations that are too often either brief or convoluted and Sentence Correction explanations that are too cryptic.
3. In the Reading Comprehension section, questions are not fully presented in order of progressive difficulty, contrary to what the back cover of the book claims.

Despite these flaws, the 2018 GMAT Official Guide is an essential source of GMAT practice. We believe that every GMAT aspirant must use this book (or the prior edition). For the best value, we recommend purchasing this book as part of 2018 GMAT Official Guide Bundle. If you already have the 2017 edition of this book, however, the replacement of 61 math questions and 61 verbal questions is not sufficient to make this edition worth purchasing.

## Preview of 2017 GMAT Official Guide Math

In this third post of this series of exclusive previews of the 2017 GMAT Official Guides, we now turn to the math section of the main Official Guide. We will focus on how the 2017 GMAT Official Guide differs from the 2016 edition in terms of math question difficulty and math concepts.

## Problem Solving – Difficulty

Both the 2017 and 2016 editions of the GMAT Official Guide contain 254 Problem Solving questions, including the identical 24 Problem Solving questions in the Diagnostic Exam portion of the guides. But the allocation of question difficulty, as assigned by the GMAC, has noticeably shifted towards Easy difficulty. Part of this change resulted from the GMAC downgrading 8 questions from Medium difficulty (in 2016) to Easy (in 2017).

Difficulty 2017 2016 Change
Easy 82 63 +19
Medium 55 60 (5)
Hard 117 131 (14)
Total 254 254

A total of 36 new Problem Solving questions, which we have never seen before, appear in the 2017 GMAT Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 18 / 8 / 10. This is in lieu of 36 questions from the 2016 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 7 / 5 / 24. We are disappointed to see that Hard difficulty has a net loss of 14 questions, although we would rate most of the 24 removed Hard questions as actually Medium difficulty. Let’s further break down how each of these difficulty categories has changed.

### Easy Problem Solving

18 new questions

Subtractions:
7 questions removed

Net change: +19 questions

### Medium Problem Solving

8 new questions

Subtractions:
5 questions removed

Net change: -5 questions

### Hard Problem Solving

10 new questions

Subtractions:
24 questions removed

Net change: -14 questions

## Problem Solving – Concepts

Let’s now consider changes in the concepts of the 36 new (in 2017) and the 36 removed (from 2016) Problem Solving questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2017 2016 Change
Arithmetic Basic 2 0 +2
Arithmetic Divisibility/Factors/Mult. 1 2 (1)
Arithmetic Exponents & Roots 1 1
Arithmetic Fractions & Ratios 3 6 (3)
Arithmetic Percents 5 6 (1)
Algebra Inequalities 2 0 +2
Algebra Linear Equations 2 3 (1)
Algebra Simultaneous Equations 2 2
Algebra Variables in Answers 3 1 +2
Geometry Circles 1 1
Geometry Coordinate 0 1 (1)
Statistics Averages 2 3 (1)
Statistics Other 3 1 +2
Word Problems Combinatorics 1 0 +1
Word Problems Functions & Sequences 1 1
Word Problems Groups/Sets 1 2 (1)
Word Problems Probability 2 2
Word Problems Rate & Work 2 2

Although we cannot draw definite conclusions from this data about question composition on the GMAT, what stands out most is the decrease in fractions & ratios questions.

## Data Sufficiency – Difficulty

Both the 2017 and 2016 editions of the GMAT Official Guide contain 198 Data Sufficiency questions, including the identical 24 Data Sufficiency questions in the Diagnostic Exam portion of the guides. As with Problem Solving, the allocation of question difficulty has noticeably shifted away from Hard. No questions have been reclassified in terms of difficulty.

Difficulty 2017 2016 Change
Easy 50 46 +4
Medium 51 41 +10
Hard 97 111 (14)
Total 198 198

A total of 26 new Data Sufficiency questions, which we have never seen before, appear in the 2017 GMAT Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 9 / 12 / 5. This is in lieu of 26 questions from the 2016 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 5 / 2 / 19. We are disappointed to see that Hard difficulty has a net loss of 14 questions, although we would rate most of the 19 removed Hard questions as actually Medium difficulty. Let’s further break down how each of these difficulty categories has changed.

### Easy Data Sufficiency

9 new questions

Subtractions:
5 questions removed

Net change: +4 questions

### Medium Data Sufficiency

12 new questions

Subtractions:
2 questions removed

Net change: +10 questions

### Hard Data Sufficiency

5 new questions

Subtractions:
19 questions removed

Net change: -14 questions

## Data Sufficiency – Concepts

Let’s now consider changes in the concepts of the 26 new (in 2017) and the 26 removed (from 2016) Data Sufficiency questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2017 2016 Change
Arithmetic Basic 5 2 +3
Arithmetic Divisibility/Factors/Mult. 1 0 +1
Arithmetic Exponents & Roots 3 2 +1
Arithmetic Fractions & Ratios 1 1
Arithmetic Percents 3 2 +1
Arithmetic Pos/Neg & Odd/Even 1 4 (3)
Arithmetic Primes 1 0 +1
Algebra Linear Equations 1 0 +1
Algebra Simultaneous Equations 1 2 (1)
Geometry Circles 0 2 (2)
Geometry Triangles 3 1 +2
Geometry Other 1 0 +1
Statistics All 1 0 +1
Word Problems Groups/Sets 2 3 (1)
Word Problems Probability 1 1
Word Problems Revenue/Profit/Interest 0 3 (3)

Although we again cannot draw definite conclusions from this data about question composition on the GMAT, what stands out most is the decrease in odd/even and revenue/profit concepts .

## Removed Questions

Here is the list of the math questions that have been removed from the 2016 edition of the GMAT Official Guide. We’ll publish a list of the new math questions in the 2017 GMAT Official Guide after it publicly releases.

### Problem Solving – 36 questions removed:

26, 34, 37, 40, 41, 47, 54, 65, 72, 79, 80, 103, 110, 111, 150, 157, 161, 169, 176, 179, 180, 184, 186, 187, 194, 197, 198, 199, 200, 202, 203, 207, 208, 209, 227, 228

### Data Sufficiency – 26 questions removed:

1, 3, 9, 17, 33, 44, 65, 74, 78, 81, 109, 113, 131, 139, 140, 141, 150, 151, 154, 158, 159, 165, 166, 170, 173, 174

## Summary

In the 2017 GMAT Official Guide, the GMAC has replaced a total of 62 Quant questions, representing just over 15% of the questions (excluding the Diagnostic Exam section). The changes in this edition are far less significant than the changes we saw between the 2015 to the 2016 editions of this book. Nonetheless, what stands out is the net loss of 28 Hard Quant questions, as rated by the GMAC. GMAT Genius will continue to offer detailed analysis of the 2017 GMAT Official Guides in the coming weeks. Stay tuned!

## Preview of 2017 GMAT Quantitative Official Guide

GMAT Genius has been working closely with the publisher of the Official Guides for GMAT Review over the past few weeks, in advance of the June 7 release of the 2017 editions, to help improve the online version of the Official Guides. In doing so, we have thoroughly analyzed the 2017 versions of the GMAT Official Guides, and want to give you an overview of what to expect. In this post, we will focus specifically on how the 2017 GMAT Quantitative Official Guide differs from the 2016 edition in terms of question difficulty and math concepts.

## Problem Solving – Difficulty

Both the 2017 and 2016 editions of the GMAT Quantitative Official Guide contain 176 Problem Solving questions. The allocation of question difficulty, as assigned by the GMAC, has slightly shifted away from Medium. Part of this change resulted from the GMAC downgrading two questions from Medium difficulty (in the 2016 edition) to Easy (in the 2017 edition).

Difficulty 2017 2016 Change
Easy 85 82 +3
Medium 52 57 (5)
Hard 39 37 +2
Total 176 176

A total of 26 new Problem Solving questions, which we have never seen before, appear in the 2017 GMAT Quantitative Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 17 / 5 / 4. Of the four new Hard questions, we actually consider one Easy and one Medium. These new questions are in lieu of 26 questions from the 2016 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 16 / 8 / 2. Let’s further break down how each of these difficulty categories has changed.

### Easy Problem Solving

17 new questions

Subtractions:
16 questions removed

Net change: +3 questions

### Medium Problem Solving

5 new questions

Subtractions:
8 questions removed

Net change: -5 questions

### Hard Problem Solving

4 new questions

Subtractions:
2 questions removed

Net change: +2 questions

## Problem Solving – Concepts

Let’s now consider changes in the concepts of the 26 new (in 2017) and the 26 removed (from 2016) Problem Solving questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2017 2016 Change
Arithmetic Basic 5 1 +4
Arithmetic Divisibility & Factors 1 2 (1)
Arithmetic Exponents & Roots 1 3 (2)
Arithmetic Fractions & Ratios 3 2 +1
Arithmetic Percents 3 4 (1)
Algebra Linear Equations 0 3 (3)
Algebra Simultaneous Equations 1 0 +1
Algebra Variables in Answers 1 1
Geometry All Geometry 3 3
Statistics Averages 2 1 +1
Statistics Other Statistics 2 1 +1
Word Problems Combinatorics 1 0 +1
Word Problems Groups/Sets 0 1 (1)
Word Problems Rate & Work 1 2 (1)

Although we cannot draw definite conclusions from this data about question composition on the GMAT, what stands out is the decrease in algebraic linear equations and the increase in basic arithmetic.

## Data Sufficiency – Difficulty

Both the 2017 and 2016 editions of the GMAT Quantitative Official Guide contain 124 Data Sufficiency questions. The allocation of question difficulty, as assigned by the GMAC, has noticeably shifted away from Hard. This is a bit misleading, however, because we would rate all five of the new Hard questions as Hard, whereas we would rate only three of the 15 removed Hard questions as actually Hard.

Difficulty 2017 2016 Change
Easy 26 22 +4
Medium 31 25 +6
Hard 67 77 (10)
Total 124 124

A total of 19 new Data Sufficiency questions, which we have never seen before, appear in the 2017 GMAT Quantitative Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 7 / 7 / 5. This is in lieu of 19 questions from the 2016 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 3 / 1 / 15. Since no questions have been assigned a different difficulty, these new and removed questions alone account for the differences in the number of questions per difficulty level.

## Data Sufficiency – Concepts

Let’s now consider changes in the concepts of the 19 new (in 2017) and the 19 removed (from 2016) Data Sufficiency questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2017 2016 Change
Arithmetic Divisibility/Factors/Mult. 2 1 +1
Arithmetic Exponents & Roots 1 1
Arithmetic Fractions & Ratios 1 1
Arithmetic Pos/Neg & Odd/Even 1 1
Arithmetic Primes 1 1
Algebra Inequalities 2 2
Algebra Linear Equations 0 1 (1)
Algebra Simultaneous Equations 2 1 +1
Geometry All Geometry 3 3
Statistics All Statistics 1 2 (1)
Word Problems Functions & Sequences 1 0 +1
Word Problems Groups/Sets 1 2 (1)
Word Problems Revenue/Profit 1 1
Word Problems Rate & Work 1 1

No specific trends stand out from this data about question composition.

## Removed Questions

Here is the list of the questions that have been removed from the 2016 edition of the GMAT Quantitative Official Guide. We’ll publish a list of the new questions in the 2017 GMAT Quantitative Official Guide after it publicly releases.

### Problem Solving – 26 questions removed:

14, 23, 27, 30, 32, 36, 37, 41, 43, 44, 46, 53, 54, 56, 57, 66, 91, 92, 103, 112, 123, 130, 137, 138, 168, 170

### Data Sufficiency – 19 questions removed:

14, 19, 22, 33, 51, 54, 59, 61, 67, 80, 83, 87, 90, 97, 100, 101, 103, 107, 114

## Summary

In the 2017 GMAT Quantitative Official Guide, the GMAC has replaced a total of 45 questions, representing 15% of the questions. The changes in this edition are far less significant than the changes we saw between the 2015 to the 2016 editions of this book. GMAT Genius will offer much more detailed analysis and critique of the 2017 GMAT Official Guides in the coming weeks. Stay tuned!

## Review of 2016 GMAT Official Guide

GMAT Genius worked closely with the publishers of the 2016 GMAT Official Guide, upon their request, in the weeks leading up to the release of the book to help improve the online versions of the Official Guides. This gave us an opportunity to thoroughly analyze the 2016 GMAT Official Guide, and we want to share our insights with you. Feel free to read our detailed analysis or to skip down to our conclusions.

## Overview of the 2016 GMAT Official Guide

The Official Guides for GMAT Review contain retired real GMAT questions, and are an essential component of your GMAT preparations. The GMAC places questions in order of increasing difficulty, based on its assessment of difficulty. This book has no overlap of practice questions with the Quant and Verbal Official Guides.

Unlike the 2015 edition, which contained no new questions, the 2016 GMAT Official Guide contains 201 new questions out of the 907 total questions. Excluding the 100 questions in the Diagnostic Exam section of the book, the new questions represent 25% new content as promised by the GMAC. These are brand new questions that we have not encountered before; they are not questions recycled from older GMAC resources.

## Problem Solving

The 2016 GMAT Official Guide contains 254 Problem Solving questions, including the 24 Problem Solving questions in the Diagnostic Exam portion of the book. Here’s how the GMAC classifies question difficulty into three categories, along with the changes by category from the 2015 edition:

Difficulty Number Change
Easy 63 +18
Medium 60 (41)
Hard 131 +23

The Problem Solving section contains 57 new questions, with difficulty of Easy / Medium / Hard as follows: 21 / 24 / 12. This is in lieu of 57 questions from the 2015 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 12 / 20 / 25. A total of 45 questions have been assigned a different difficulty than they were in the 2015 edition. Specifically, 9 Medium questions have been downgraded to Easy and 36 Medium questions have been upgraded to Hard.

GMAT Genius classifies question difficulty into five categories. Our assessment of this section skews significantly easier, and contains notable differences from the GMAC’s assessment. Our difficulty assessment is only 55.5% correlated with the GMAC’s assessment, demonstrating tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Change
Super Easy 11 (4)
Easy 71 (3)
Medium 116
Hard 41 +6
Very Hard 15 +1

Although many math questions entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. What stands out most is the increase in statistical average questions. Here’s how we classify the 254 Problem Solving questions by concept, along with the changes from the 2015 edition:

Type Concept Number Change
Arithmetic Basic 6 (1)
Arithmetic Absolute Value 3 (1)
Arithmetic Divisibility 6 (2)
Arithmetic Exponents & Roots 22 +1
Arithmetic Factors & Multiples 10 +1
Arithmetic Fractions 20
Arithmetic Percents 21 +2
Arithmetic Pos/Neg & Odd/Even 2
Arithmetic Primes 4 (1)
Arithmetic Ratios 13 (3)
Algebra Formulas 6 +2
Algebra Inequalities 3 (3)
Algebra Linear Equations 8 (1)
Algebra Simultaneous Equations 8 (3)
Algebra Variables in Answers 5 +1
Geometry 3D 6
Geometry Circles 5 +1
Geometry Coordinate 8
Geometry Rectangles 7 +1
Geometry Triangles 7 +1
Geometry Other 1 (2)
Statistics Averages 18 +4
Statistics Other 4
Word Problems Combinatorics 6 +1
Word Problems Functions & Sequences 11 +2
Word Problems Groups / Sets 8
Word Problems Interest 4 +1
Word Problems Mixture 0 (1)
Word Problems Probability 8
Word Problems Revenue & Profit 4 +1
Word Problems Rate & Work 12 (1)

Here’s a list of the 57 new Problem Solving questions: 1, 2, 3, 11, 13, 14, 15, 17, 18, 21, 25, 27, 30, 31, 33, 38, 39, 43, 44, 45, 55, 56, 57, 59, 60, 61, 63, 66 to 70, 73, 76, 82, 83, 85 to 89, 91, 97, 99, 107, 108, 111, 114, 117, 122, 125, 134, 136, 137, 139, 142, 153

## Data Sufficiency

The 2016 GMAT Official Guide contains 198 Data Sufficiency questions, including the 24 Data Sufficiency questions in the Diagnostic Exam portion of the book. Here’s how the GMAC classifies question difficulty into three categories, along with the changes by category from the 2015 edition:

Difficulty Number Change
Easy 46 +14
Medium 41 (30)
Hard 111 +16

The Data Sufficiency section contains 44 new questions, with difficulty of Easy / Medium / Hard as follows: 17 / 12 / 15. This is in lieu of 44 questions from the 2015 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 10 / 11 / 23. A total of 31 questions have been assigned a different difficulty than they were in the 2015 edition. Specifically, 7 Medium questions have been downgraded to Easy and 24 Medium questions have been upgraded to Hard.

GMAT Genius classifies question difficulty into five categories. Our assessment skews significantly easier, and contains notable differences from the GMAC’s assessment. Our difficulty assessment is only 56.4% correlated with the GMAC’s assessment, demonstrating tremendous subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Change
Super Easy 8
Easy 49 +2
Medium 95 (8)
Hard 40 +7
Very Hard 6 (1)

Although many math questions entail multiple math concepts, GMAT Genius classifies questions based on our assessment of the primary math concept. What stands out most is the decrease in simultaneous equation questions. Here’s how we classify the 198 Data Sufficiency questions by concept, along with the changes from the 2015 edition:

Type Concept Number Change
Arithmetic Basic 10 (3)
Arithmetic Absolute Value 0 (1)
Arithmetic Divisibility 5
Arithmetic Exponents & Roots 12 +2
Arithmetic Factors & Multiples 3
Arithmetic Fractions & Ratios 11 (2)
Arithmetic Odd/Even 6 (1)
Arithmetic Percents 15 +4
Arithmetic Positive/Negative 6 +1
Algebra Inequalities 11 +1
Algebra Linear Equations 9 +1
Algebra Simultaneous Equations 10 (7)
Geometry Circles 7
Geometry Coordinate 7 +2
Geometry Rectangles 4 +2
Geometry Triangles 8 (2)
Geometry Other 5 +1
Statistics Averages 14 (1)
Statistics Other 10 +2
Word Problems Functions & Sequences 5
Word Problems Groups / Sets 12 +1
Word Problems Interest 4
Word Problems Probability 3
Word Problems Revenue & Profit 7 +1
Word Problems Rate & Work 8 (1)

Here’s a list of the 44 new Data Sufficiency questions: 7, 10, 12, 14, 15, 16, 18 to 21, 23, 26, 27, 29, 34, 37 to 41, 46, 48, 49, 51, 54, 55, 60, 64, 67, 73, 77, 80, 83, 84, 86, 92, 94, 115, 121, 134 to 137, 150

## Sentence Correction

The 2016 GMAT Official Guide contains 158 Sentence Correction questions, including the 18 Sentence Correction questions in the Diagnostic Exam portion of the book. Here’s how the GMAC classifies question difficulty into three categories, along with the changes by category from the 2015 edition:

Difficulty Number Change
Easy 35 +3
Medium 45 (25)
Hard 78 +22

The Sentence Correction section contains 35 new questions, with difficulty of Easy / Medium / Hard as follows: 10 / 8 / 17. This is in lieu of 35 questions from the 2015 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 2 / 16 / 17. A total of 33 questions have been assigned a different difficulty than they were in the 2015 edition, including 23 Medium questions (in the 2015 edition) that have been upgraded to Hard.

GMAT Genius classifies question difficulty into five categories. Our assessment skews noticeably easier, and contains notable differences from the GMAC. Our difficulty assessment is only 56.7% correlated with the GMAC’s assessment, clearly showing that there is subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Change
Super Easy 1 +1
Easy 49 +3
Medium 62 (2)
Hard 39 (3)
Very Hard 7 +1

Although Sentence Correction questions typically entail multiple grammar concepts, GMAT Genius classifies questions based on our assessment of the primary tested concept. Parallel construction clearly stands out as the most prominent category. Here’s how we classify the 158 Sentence Correction questions by concept, along with the changes from the 2015 edition:

Concept Number Change
Verb Agreement 18 +2
Verb Tense 21
Pronoun Ambiguity 11 (1)
Pronoun Agreement 2 (1)
Parallel Construction 48 (2)
Misplaced Modifiers 14 +2
Idioms 8 (3)
Comparison & Quantity 15
Expression & Meaning 21 +3

Here’s a list of the 35 new Sentence Correction questions: 2, 4, 7, 10, 13, 18, 21, 23, 27, 28, 31, 35, 37, 42, 46, 52, 63, 66, 73, 80, 86, 90, 97, 101, 111, 116, 120, 124, 126, 128, 132, 133, 136, 137, 138

## Critical Reasoning

The 2016 GMAT Official Guide contains 141 Critical Reasoning questions, including the 17 Critical Reasoning questions in the Diagnostic Exam portion of the book. Here’s how the GMAC classifies question difficulty into three categories, along with the changes by category from the 2015 edition:

Difficulty Number Change
Easy 40 (1)
Medium 45 (6)
Hard 56 +7

The Critical Reasoning section contains 34 new questions, with difficulty of Easy / Medium / Hard as follows: 7 / 16 / 11. This is in lieu of 34 questions from the 2015 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 7 / 14 / 13. A total of 12 questions have been assigned a different difficulty than they were in the 2015 edition, including 10 Medium questions (in the 2015 edition) that have been upgraded to Hard.

GMAT Genius classifies question difficulty into five categories. Our assessment skews slightly easier, but contains notable differences from the GMAC. Our difficulty assessment is 72.8% correlated with the GMAC’s assessment, clearly indicating subjectivity involved in assessing question difficulty. Here’s our breakdown:

Difficulty Number Change
Super Easy 0
Easy 45 +5
Medium 51 (3)
Hard 33 (5)
Very Hard 12 +3

We have grouped the questions based on the question type categorization that GMAT Genius uses for Critical Reasoning. Weaken and Strengthen questions continue to dominate, but Assumption has noticeably increased. Here’s how we classify the 141 Critical Reasoning questions by concept, along with the changes from the 2015 edition:

Concept Number Change
Weaken 25 (2)
Strengthen 25
Assumption 16 +4
Reasoning 8
Conclusion 7 (3)
Explain 18 +1
Evaluate 17 (1)
Boldface 9
Complete the Passage 16 +1

Here’s a list of the 34 new Critical Reasoning questions: 1 to 4, 8, 21, 30, 37, 39, 41, 43, 48, 49, 53, 55, 57, 58, 60, 63, 65, 67, 70, 76, 77, 79, 81, 84, 94, 97, 100, 106, 109, 121, 124

The 2016 GMAT Official Guide contains 156 Reading Comprehension questions across 29 passages, including the 17 Reading Comprehension questions in 3 passages in the Diagnostic Exam portion of the book. Here’s how the GMAC classifies question difficulty into three categories, along with the changes by category from the 2015 edition:

Difficulty Number Change
Easy 54 +24
Medium 65 (15)
Hard 37 (9)

The Reading Comprehension section contains 31 new questions in 6 passages, with difficulty of Easy / Medium / Hard as follows: 9 / 6 / 16. This is in lieu of 31 questions in 6 passages from the 2015 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 3 / 8 / 20. In this edition, the GMAC has downgraded the difficulty level of 23 questions.

GMAT Genius classifies question difficulty into five categories. Whereas the GMAC assigns the same difficulty to all questions for a given passage (except in the Diagnostic Exam section), GMAT Genius assesses the difficulty of each question individually. Our assessment skews slightly harder, but contains notable differences from the GMAC. Our difficulty assessment is only 48.9% correlated with the GMAC’s assessment, in large part due to different difficulty assessment methodologies. Here’s our breakdown:

Difficulty Number Change
Super Easy 5 (2)
Easy 28 +4
Medium 73 (2)
Hard 42
Very Hard 8

We have grouped the questions based on the question type categorization that GMAT Genius uses for Reading Comprehension. Specific Reference and Inference questions continue to dominate, but Specific Reference declined noticeably. Here’s how we classify the 156 Reading Comprehension questions by concept, along with the changes from the 2015 edition:

Concept Number Change
Primary Purpose 24 +1
Author’s Tone 10 +2
Organization 4 +1
Function 20 +4
Specific Reference 60 (8)
Inference 30
Critical Reasoning 8

Here’s a list of the 31 new Reading Comprehension questions: 8 to 10, 42 to 47, 96 to 101, 107 to 112, 130 to 139

## Integrated Reasoning

The 2016 GMAT Official Guide provides an 11-page overview of the Integrated Reasoning section, along with online access to 50 Integrated Reasoning practice questions. The IR set includes 12 new questions that we have not seen before, replacing 12 questions that were in the 2015 edition. The 50 questions consist of the following four types:

Question Type Number New Qs
Graphics Interpretation 10 4
Multi-Source Reasoning 18 4
Table Analysis 6 1
Two-Part Analysis 16 3

Here’s a list of the 12 new Integrated Reasoning questions: 12 to 15, 22, 29, 32, 33, 34, 44, 49, 50

## Other Notes

The 2016 GMAT Official Guide contains a 40-page Math Review section that provides a very high-level overview of the math concepts tested on the GMAT. This math review will be highly inadequate except perhaps for the most advanced math students. Similarly, the brief introductions to the concepts tested on the verbal section are highly inadequate. We recommend that you use additional study materials to learn the math and verbal concepts.

Although all questions include answer explanations, many GMAT test takers are far from satisfied with these explanations. Math explanations can be brief and hard-to-understand for non-advanced students, and are sometimes convoluted or inefficient. Most GMAT test takers consider the Sentence Correction explanations quite cryptic. The Critical Reasoning and Reading Comprehension explanations, however, are reasonably good overall.

The book includes an access code that provides 12-month usage of an online version of this Official Guide. Since the GMAT is a computer-based test, we believe that it is advisable to work though the questions online. We recommend that you use Exam Mode rather than Practice Mode, since we recommend that students practice using timed question sets.

The online practice interface has improved from last year’s version. The publishers implemented some of our recommendations, but they did not incorporate many of our functionality improvement suggestions. One major flaw that we discussed with the book publishers, but that has not been fixed, is the inaccurate timing for “Previous Sessions.” Timing statistics are accurate when you initially review a question set, but the timing per question data is inaccurate when you later access the same question set.

If you already have the 2015 edition of this book, it is debatable whether the addition of 101 new math questions and 100 new verbal questions makes this book worth purchasing. Our opinion is that advanced students will not find enough additional challenging practice to justify the purchase, but other students could purchase the book for additional practice given the relatively low cost.

## Conclusions

The 2016 GMAT Official Guide has three primary weaknesses, in our opinion:
1) An insufficient amount of difficult practice questions, particularly based on GMAT Genius’ assessment of difficulty
2) Math answer explanations that are too often either brief or convoluted and Sentence Correction explanations that are too cryptic
3) Inaccurate timing data for Previous Sessions and inadequate functionality in the online practice interface

Despite its flaws, the 2016 GMAT Official Guide is an essential source of GMAT practice. We are pleased to see 25% brand new questions in the 2016 edition. We believe that every GMAT aspirant must use this book (or the prior edition). For these reasons, we give this book a 5-star rating. For the best value, we recommend purchasing this book as part of the 2016 GMAT Official Guide Bundle.

You can read this review on Amazon. If you find our review and analysis helpful, please let other Amazon customers know by clicking the Yes button at the bottom of our review.

## Preview of 2016 GMAT Official Guide Math

In this third post of this series of exclusive previews of the 2016 GMAT Official Guides, we now turn to the math section of the main Official Guide. We will focus on how the 2016 GMAT Official Guide differs from the 2015 edition in terms of math question difficulty and math concepts.

## Problem Solving – Difficulty

Both the 2015 and 2016 editions of the GMAT Official Guide contain 230 Problem Solving questions, excluding the identical 24 Problem Solving questions in the Diagnostic Exam portion of the guides. But the allocation of question difficulty, as assigned by the GMAC, has noticeably shifted. In particular, the Easy and Hard categories have expanded whereas the Medium category has shrunk considerably. A big portion of these change resulted from the GMAC upgrading 36 questions from Medium difficulty (in the 2015 edition) to Hard (in the 2016 edition).

Difficulty 2016 2015 Change
Easy 55 37 +18
Medium 52 93 (41)
Hard 123 100 +23
Total 230 230

A total of 57 brand new Problem Solving questions, which we have never seen before, appear in the 2016 GMAT Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 21 / 24 / 12. This is in lieu of 57 questions from the 2015 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 12 / 20 / 25. Let’s further break down how each of these difficulty categories has changed.

### Easy Problem Solving

21 new questions

Subtractions:
12 questions removed

Net change: +18 questions

### Medium Problem Solving

24 new questions

Subtractions:
20 questions removed

Net change: -41 questions

### Hard Problem Solving

12 new questions

Subtractions:
25 questions removed

Net change: +23 questions

## Problem Solving – Concepts

Let’s now consider changes in the concepts of the 57 new (in 2016) and the 57 removed (from 2015) Problem Solving questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2016 2015 Change
Arithmetic Basic 3 5 (2)
Arithmetic Absolute Value 0 1 (1)
Arithmetic Divisibility & Factors 2 3 (1)
Arithmetic Exponents & Roots 4 3 1
Arithmetic Fractions & Ratios 3 5 (2)
Arithmetic Percents 4 2 2
Arithmetic Positive/Negative 1 1
Algebra Formulas 2 0 2
Algebra Inequalities 1 4 (3)
Algebra Linear Equations 2 3 (1)
Algebra Simultaneous Equations 2 5 (3)
Geometry Various 15 14 1
Statistics Averages 5 1 4
Statistics Other 1 1
Word Problems Functions & Sequences 2 0 2
Word Problems Other Various 8 7 1

Although we cannot draw definite conclusions from this data about question composition on the GMAT, what stands out is the decrease in algebraic inequalities and simultaneous equations, the decrease in arithmetic fundamentals, and the increase in averages.

## Data Sufficiency – Difficulty

Both the 2015 and 2016 editions of the GMAT Official Guide contain 174 Data Sufficiency questions, excluding the identical 24 Data Sufficiency questions in the Diagnostic Exam portion of the guides. As with Problem Solving, the allocation of question difficulty has noticeably shifted. Once again, the Easy and Hard categories have expanded whereas the Medium category has shrunk considerably. A big portion of these change resulted from the GMAC upgrading 24 questions from Medium difficulty (in the 2015 edition) to Hard (in the 2016 edition).

Difficulty 2016 2015 Change
Easy 38 24 +14
Medium 34 64 (30)
Hard 102 86 +16
Total 174 174

A total of 44 brand new Data Sufficiency questions, which we have never seen before, appear in the 2016 GMAT Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 17 / 12 / 15. This is in lieu of 44 questions from the 2015 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 10 / 11 / 23. Let’s further break down how each of these difficulty categories has changed.

### Easy Data Sufficiency

17 new questions

Subtractions:
10 questions removed

Net change: +14 questions

### Medium Data Sufficiency

12 new questions

Subtractions:
11 questions removed

Net change: -30 questions

### Hard Data Sufficiency

15 new questions

Subtractions:
23 questions removed

Net change: +16 questions

## Data Sufficiency – Concepts

Let’s now consider changes in the concepts of the 44 new (in 2016) and the 44 removed (from 2015) Data Sufficiency questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2016 2015 Change
Arithmetic Basic 0 4 (4)
Arithmetic Absolute Value 0 1 (1)
Arithmetic Exponents 4 2 2
Arithmetic Fractions & Ratios 1 3 (2)
Arithmetic Percents 6 2 4
Arithmetic Positive/Negative 2 1 1
Algebra Simultaneous Equations 1 8 (7)
Algebra Other 7 5 2
Geometry Coordinate 3 1 2
Geometry Other 6 5 1
Statistics Averages 2 3 (1)
Statistics Other 2 0 2
Word Problems Various 10 9 1

Although we again cannot draw definite conclusions from this data about question composition on the GMAT, what clearly stands out is the decrease in algebraic simultaneous equations and basic arithmetic concepts, offset by an increase in percents.

## Removed Questions

Here is the list of the math questions that have been removed from the 2015 edition of the GMAT Official Guide. We’ll publish a list of the new math questions in the 2016 GMAT Official Guide after it publicly releases.

### Problem Solving – 57 questions removed:

1, 2, 3, 5, 6, 23, 24, 28, 29, 32, 33, 35, 38, 39, 40, 43, 45, 47, 48, 50, 53, 62, 73, 78, 86, 90, 96, 103, 104, 111, 113, 121, 147, 152, 153, 159, 161, 165, 167, 171, 173, 175, 176, 179, 184, 187, 191, 192, 195, 197, 201, 202, 205, 220, 221, 225, 227

### Data Sufficiency – 44 questions removed:

1, 2, 3, 6, 8, 13, 16, 17, 19, 20, 30, 36, 43, 45, 50, 56, 61, 72, 86, 87, 88, 89, 104, 106, 107, 112, 115, 121, 132, 136, 138, 140, 145, 148, 151, 153, 155, 156, 158, 160, 161, 162, 165, 174

## Key Takeaways

Keep in mind that we cannot draw firm conclusions about the GMAC’s intent in making changes to the question composition in the 2016 GMAT Official Guide. That said, we can observe certain trends and speculate on what those changes may imply.

Between Problem Solving and Data Sufficiency, the GMAC has upgraded 60 questions from Medium difficulty to Hard. We can only presume that the GMAC is moving away from the trend of recent years of increasing the difficulty of the math section. If correct, this would bring welcome relief to many future GMAT hopefuls.

The changes in concepts as discussed above seem consistent with what we’ve observed in the 2016 Quantitative Official Guide. Simultaneous equations, in particular, have been reduced significantly. The GMAC really seems to be moving towards math questions that require more analytical reasoning to solve rather than rote usage of formulas and fundamental math techniques.

We’re still working our way through the Verbal sections of the 2016 GMAT Official Guide, and will post our analysis as soon as we can. Stay tuned!

## Sneak Preview of 2016 GMAT Quantitative Official Guide

I have been working closely with the publisher of the Official Guide for GMAT Review over the past few weeks, in advance of the June 8 release of the 2016 editions, to help improve the online version of the Official Guides. In doing so, I have thoroughly analyzed the 2016 versions of the GMAT Official Guides, and want to give you an overview of what to expect. Out of respect for the GMAC, I cannot share specific questions. In this post, we will instead focus specifically on how the 2016 GMAT Quantitative Official Guide differs from the 2015 edition in terms of question difficulty and math concepts.

## Problem Solving – Difficulty

Both the 2015 and 2016 editions of the GMAT Quantitative Official Guide contain 176 Problem Solving questions. But the allocation of question difficulty, as assigned by the GMAC, has noticeably shifted. In particular, the Easy category has expanded whereas the Medium category has shrunk. A big portion of these change resulted from the GMAC downgrading 10 questions from Medium difficulty (in the 2015 edition) to Easy (in the 2016 edition). Interestingly, one Hard question (#159 in the 2015 edition) has also been downgraded all the way to Easy.

Difficulty 2016 2015 Change
Easy 82 67 +15
Medium 57 74 (17)
Hard 37 35 +2
Total 176 176

A total of 44 brand new questions, which we have never seen before, appear in the 2016 GMAT Quantitative Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 22 / 13 / 9. This is in lieu of 44 questions from the 2015 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 17 / 20 / 7. Let’s further break down how each of these difficulty categories has changed.

### Easy Problem Solving

22 new questions

Subtractions:
17 questions removed

Net change: +15 questions

### Medium Problem Solving

13 new questions

Subtractions:
20 questions removed

Net change: -17 questions

### Hard Problem Solving

9 new questions

Subtractions:
7 questions removed

Net change: +2 questions

## Problem Solving – Concepts

Let’s now consider changes in the concepts of the 44 new (in 2016) and the 44 removed (from 2015) Problem Solving questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2016 2015 Change
Arithmetic Basic 2 2
Arithmetic Absolute Value 2 0 2
Arithmetic Divisibility 1 1
Arithmetic Exponents 3 4 (1)
Arithmetic Fractions & Ratios 4 2 2
Arithmetic Percents 3 5 (2)
Arithmetic Positive/Negative 1 1
Algebra Formulas 2 0 2
Algebra Inequalities 2 2
Algebra Linear Equations 2 4 (2)
Algebra Simultaneous Equations 2 4 (2)
Geometry Coordinate 1 1
Geometry Other 4 4
Statistics Averages 2 4 (2)
Statistics Other 0 1 (1)
Word Problems Combinatorics 2 1 1
Word Problems Functions & Sequences 5 1 4
Word Problems Groups (Sets) 1 1
Word Problems Interest 1 0 1
Word Problems Revenue & Profit 1 2 (1)
Word Problems Rate & Work 2 3 (1)

Although we cannot draw definite conclusions from this data about question composition on the GMAT, what clearly stands out is the decrease in algebraic equations and the increase in functions and sequences.

## Data Sufficiency – Difficulty

Both the 2015 and 2016 editions of the GMAT Quantitative Official Guide contain 124 Data Sufficiency questions. As with Problem Solving, the allocation of question difficulty has noticeably shifted. Once again, the Easy category has expanded whereas the Medium category has shrunk. Interestingly, the GMAC has upgraded 23 Medium questions (from the 2015 edition) to Hard.

Difficulty 2016 2015 Change
Easy 22 9 +13
Medium 25 42 (17)
Hard 77 73 +4
Total 124 124

A total of 31 brand new questions, which we have never seen before, appear in the 2016 GMAT Quantitative Official Guide, with difficulty ratings of Easy / Medium / Hard as follows: 14 / 11 / 6. This is in lieu of 31 questions from the 2015 edition that have been removed, with difficulty ratings of Easy / Medium / Hard as follows: 1 / 6 / 24. Let’s further break down how each of these difficulty categories has changed.

### Easy Data Sufficiency

14 new questions

Subtractions:
1 question removed

Net change: +13 questions

### Medium Data Sufficiency

11 new questions

Subtractions:
6 questions removed

Net change: -17 questions

### Hard Data Sufficiency

6 new questions

Subtractions:
24 questions removed

Net change: +4 questions

## Data Sufficiency – Concepts

Let’s now consider changes in the concepts of the 31 new (in 2016) and the 31 removed (from 2015) Data Sufficiency questions. GMAT Genius classifies questions based on their primary and secondary concepts. In order to observe trends, we have condensed our categorization as follows:

Type Concept 2016 2015 Change
Arithmetic Basic 2 2
Arithmetic Absolute Value 1 0 1
Arithmetic Divisibility 0 3 (3)
Arithmetic Exponents 2 2
Arithmetic Fractions & Ratios 2 2
Arithmetic Percents 0 1 (1)
Arithmetic Positive/Negative 3 2 1
Algebra Inequalities 3 2 1
Algebra Linear Equations 0 3 (3)
Algebra Simultaneous Equations 3 6 (3)
Geometry Coordinate 3 0 3
Geometry Other 3 4 (1)
Statistics Averages 2 2 0
Statistics Other 2 0 2
Word Problems Functions & Sequences 1 0 1
Word Problems Probability 1 0 1
Word Problems Revenue & Profit 1 0 1
Word Problems Rate & Work 2 2 0

Although we again cannot draw definite conclusions from this data about question composition on the GMAT, what clearly stands out is the decrease in algebraic equations and divisibility concepts, offset by the increase in coordinate geometry and applied word problems.

## Removed Questions

Here is the list of the questions that have been removed from the 2015 edition of the GMAT Quantitative Official Guide. We’ll publish a list of the new questions in the 2016 GMAT Quantitative Official Guide after it publicly releases.

### Problem Solving – 44 questions removed:

4, 10, 11, 12, 14, 15, 16, 17, 18, 23, 25, 28, 30, 32, 37, 43, 45, 74, 75, 77, 84, 92, 99, 104, 106, 109, 111, 115, 120, 122, 123, 128, 132, 134, 138, 139, 141, 143, 144, 163, 165, 166, 167, 174

### Data Sufficiency – 31 questions removed:

3, 23, 27, 28, 30, 36, 47, 56, 57, 60, 64, 68, 71, 72, 77, 84, 86, 92, 94, 97, 98, 103, 105, 108, 109, 110, 112, 114, 119, 120, 123

## Key Takeaways

Keep in mind that we cannot draw firm conclusions about the GMAC’s intent in making changes to the question composition in the 2016 GMAT Quantitative Official Guide. That said, we can observe certain trends and speculate on what those changes may imply.

By downgrading 10 Medium Problem Solving questions to Easy while upgrading 23 Medium Data Sufficiency questions to Hard, the GMAC seems to be indicating that it considers Data Sufficiency more challenging than perhaps it did previously.

Furthermore, given the changes in concepts as discussed above, the GMAC seems to be moving away from questions that are more process-oriented (i.e. solve by following a set procedure) and towards applied questions that require more analytical reasoning to solve.

GMAT Genius will offer much more detailed analysis and critique of the 2016 GMAT Official Guides in the coming weeks. Stay tuned!

## Question Difficulty in GMAT Official Guides

Starting with the 11th Edition of the Official Guides, the Graduate Management Admission Council placed questions in order of difficulty. This is a welcome change from prior editions, because students can now choose practice questions at the appropriate difficulty level. Beginning students need not tackle difficult questions that may cause them to feel overwhelmed and frustrated, nor do advanced students need to waste time on questions that are well below their capabilities.

## Mysterious Methodology

The methodology that the GMAC uses to assign difficulty ratings to questions remains a mystery, however. Although there is a clear overall correlation between question placement and GMAT Genius’ assessment of difficulty, the correlation is far from perfect and there are many outliers, particularly with math. Let’s consider the Problem Solving section of the GMAT Official Guide (13th Ed.).

## Problem Solving Analysis

There are 230 questions in this section, excluding questions in the Diagnostic Test chapter of the book. GMAT Genius assigns difficulty at five different levels: Super Easy, Easy, Moderate, Hard, and Very Hard. To translate this into numbers, we can assign points of 1, 2, 3, 4, and 5 to each of these levels, respectively. With perfect correlation and distribution, we should see the first 46 questions (230 divided by 5) all at a Super Easy level (average difficulty 1.0), the next 46 questions all at an Easy level (average difficulty 2.0), and so on. Instead, here is how we would rank question difficulty:

OG 13E PS Super
Easy
Easy Moderate Hard Very
Hard
Average
Difficulty
1 – 46 11 29 6 0 0 1.9
47 – 92 3 18 23 2 0 2.5
93 – 138 1 10 21 13 1 3.1
139 – 184 0 12 26 4 4 3.0
185 – 230 0 5 25 11 5 3.5
Total 15 74 101 30 10 2.8

As shown in the table, average question difficulty (based on our assessment) does not increase much in the last three quintiles. In fact, the middle quintile is actually slightly harder than the fourth quintile. Surprisingly, we consider five of the top quintile questions “Easy,” including #220, which is supposed to be one of the hardest questions in the entire set. We also consider question #117 in the third quintile “Very Hard,” even though it barely passes the halfway mark. Yet the GMAC considers this question easier than #130, which we rate as “Super Easy.”

## Disparity Among Similar Questions

We see this disparity even among similar questions. Questions #178 and #186 both entail overlapping sets, and based on the ordering, the GMAC considers #186 slightly harder than #178. Yet we rate #178 as “Very Hard” and #186 as “Moderate” because the former is a complex application with three groups whereas the latter is a straightforward application with two groups. As another example, consider #137 and #203 that we described in our prior post about repetitive math questions. These two questions are very similar, yet the GMAC considers the latter much harder than the former. By contrast, we rate both these questions as “Hard” and actually consider the latter slightly easier because the numbers are much easier.

Our assessment of difficulty is admittedly somewhat subjective, but probably more realistic than how the GMAC assigns difficulty. Our difficulty ratings take into account our observations of how students tend to find the questions in term of difficulty, the ease of the calculations involved, and the length of the Official Guide explanation, except when the explanation is inefficient or misses a shortcut. For verbal questions, we also take into account the difficulty of the incorrect answers, since process of elimination can be particularly helpful on verbal. Note that our assessment of difficulty skews towards the center; a question would need to be incredibly easy or incredibly difficult to qualify as “Super Easy” or “Very Hard”, respectively. The GMAC most likely has a much greater distribution in its difficulty assignments.

## Conclusions

A key takeaway from this analysis is that you should not assume that the Official Guides are an objective measure of question difficulty. Although we don’t know how the GMAC assigns difficulty and would expect a few differences of opinion, we can confidently claim that quite a few questions are ordered incorrectly. So if you encounter a few questions in the Official Guides that are hard for you, it does not necessarily mean that all subsequent questions are beyond your reach. Another implication of this analysis is that the Official Guides do not contain enough difficult practice questions, a complaint we often hear from our advanced students. The GMAC has released two relatively new study products (Exam Pack 1 and Question Pack 1), so let’s hope that Difficult Pack 1 is in the works.

## Repetitive Math Questions in GMAT Official Guides

In your preparations for the GMAT math section, it is essential that you practice with retired real GMAT questions using the GMAT Official Guide (13th Edition) and the GMAT Quantitative Official Guide (2nd Edition). These two books provide you with a combined total of 430 Problem Solving and 322 Data Sufficiency practice questions.

## Repetitive Problem Solving Questions

One interesting observation from our analysis of these questions is the frequency with which some questions closely mirror another question. Due to copyright issues, we cannot reprint these repetitive math questions from the Official Guides. But if you have your copies handy, compare the following sets of Problem Solving questions:

• 13E #128 (page 170) vs. 2E #132 (page 79): These two questions involving combinatorics are nearly identical, even using the same numbers in the problem and in the first three answer choices (one of which is the correct answer). Only the context changes: one question involves finding the minimum number of colors for a distribution center’s coding, and the other involves finding the minimum number of letters for an experiment’s coding.
• 13E #194 (page 179) vs. 2E #165 (page 84): Both questions provide three fractions of a total amount and the remaining balance that is unaccounted for, and ask us to calculate the total amount. One question relates to the amount of a trust fund whereas the other involves the number of students in a class, but the numbers within the problems are identical (except that one total is in thousands and the other is not).
• 13E #124 (page 169) vs. 13E #133 (page 171) vs. 2E #56 (page 69): These three questions all involve calculating the number of pairs that are possible out of a larger group. Two of these questions ask about the number of table entries needed to show the mileage between any two cities, and the third asks about number of games needed so that every team in a league plays each other once. For these types of questions, we teach our students a tabular approach, a combinatorics approach, and a summation approach.
• 13E #137 (page 171) vs. 13E #203 (page 181): At first glance, these two word problems seem unrelated. But the setup for both problems is identical: we have an unknown price and quantity, and when one goes up by a specified amount the other goes down by a specified amount in order to generate an equivalent revenue amount.
• 13E #111 (page 167) vs. 13E #170 (page 176): In both cases, we have a terminating decimal in the form of 1 / (2^x * 5^y) where x and y are specified exponents. Both questions entail counting digits.
• 13E #95 (page 165) vs. 13E diagnostic #13 (page 22): Both questions entail one positive integer divided by another, resulting in a quotient and a remainder equivalent to .12. Our objective is to use the .12 to deduce the value of the divisor in one question and to identify a possible remainder in the other question.
• 13E #45 (page 158) vs. 2E #57 (page 69): Both problems give us a quadratic equation using the variable x and a constant k. Given one root of the quadratic, we must find the other solution in one problem and the value of k in the other problem.

## Repetitive Data Sufficiency Questions

Although the above are the most obvious examples of repetition in Problem Solving, there is much more repetition of concepts across questions. We also can find examples of repetition within Data Sufficiency, albeit to a lesser extent. As two obvious examples, compare the following sets of Data Sufficiency questions:

• 13E #2 (page 275) vs. 13E #21 (page 276): These two questions have identical setups, although with different numbers in different contexts. In both questions, statement 1 gives us what percent of women have a certain characteristic and statement 2 gives us what percent of men have the same characteristic. The questions both ask what percent of the total are women with that characteristic.
• 13E #57 (page 280) vs. 13E #59 (page 280): In both cases, we have two different denominations (of bills in one question and of gift certificates in the other). Statement 1 has an identical setup in both questions – the maximum number of the smaller denomination. In #57, the initial information tells us the minimum number of the larger denomination and statement 2 tells us the total value of both denominations combined. In #59, the initial information and that given in statement 2 are swapped.

## Conclusions

Why does this repetition happen? Since the GMAT tests a finite number of concepts, these concepts will inevitably appear repeatedly in various forms. But since the GMAC must produce a vast number of questions each year to ensure a fair testing environment, one way to make the question development process more efficient is to borrow heavily from other questions. We also see concepts applied repetitively in Verbal questions, but the questions themselves are not as obviously duplicative as the Math questions that we’ve discussed.

What is the implication of this? One of our “6 Habits of Highly Effective GMAT Students” is to watch out for patterns. As you work through many practice GMAT problems in the Official Guides and elsewhere, you will inevitably encounter similar concepts. With sufficient practice, you will be able to identify the approaches that are most relevant to a given problem. Of course you should not blindly follow the same methodology used on another problem, since the concepts may be applied differently. But the more adept you are at quickly recognizing the relevant approaches to apply to questions on test day, the better your GMAT score will be.