GMAT OG Quant Review, 2nd Ed: Overview
ManhattanGMAT has performed an in-depth examination of the OG Quant Review, 2nd Edition. We've matched up the 1st and 2nd editions, classified every problem by topic, run the numbers, and drawn out the insights. Download the OG Quant Review Problem Lists, which categorize new problems by question type, and read the analysis on this series of pages.
In late August, the 2nd edition of the Official Guide for GMAT Quantitative Review was released. We at Manhattan GMAT have analyzed the book in detail, as we did with the 12th edition of the main Official Guide and the 2nd edition Verbal Review. Here are our findings.
Again, Not Radically Different
Out of 300 questions, 74 (25%) are “new to this edition,” as the cover states. In other words, about three-quarters of the problems are repeats. Look at the 2nd edition primarily as a source of 74 additional OG-level practice problems.
These 74 problems are not repeated from the 11th edition of the main Official Guide. However, there seems to be a little overlap with the content of GMAT Prep exams. GMAT Prep has always overlapped somewhat with the printed OGs, so this shouldn’t be a big concern.
The removal and addition of various problems may constitute a very slight shift in the relative emphasis of certain topics and skills. However, the underlying content of problems, as well as their stylistic approach, is essentially the same across the two editions.
You should not over-interpret the changes that did occur between the 1st edition and the 2nd edition. Some variation is to be expected. Nothing in these changes indicates a notable shift in how to prepare for the exam.
Transition If And When You're Comfortable
Our advice is the same as it was with the 12th edition of the main OG and the 2nd edition Verbal Review guide. If you have been preparing with the 1st Edition Quant Review book, feel free to treat the 2nd Edition as a source of additional practice. But you do not need to switch immediately.
If your exam is near, you might consider mining the 2nd Edition for a few new problems. But your time may be better spent reviewing practice problems you have already encountered, as well as doing online practice with GMATPrep, GMATFocus, or practice exams such as ours.
Why Do We Say 74 New Questions, Not 75 As the Cover States?
We compared every problem in the 2nd edition to every problem in the 1st edition, and here’s what we found.
73 truly new problems did not exist in the 1st edition.
One "new" problem (PS #76) is almost identical to its cousin in the 1st edition.
The variable changed from x to n.
The phrasing changed in an extremely slight way: from "the length of its diagonal" to "the length of the diagonal of the square." In the first version, the antecedent of "its" is either "a square region" or the "area" of that region, so the meaning is the same.
The order and content of some of the answer choices changed a little, so that the right answer is a different letter.
But in every other way, the two problems are identical.
Since the right answer is a different letter, we are counting PS #76 as a new problem, somewhat unwillingly. This is how we got to a count of 74 problems.
Three other problems exhibited even more minor edits. We are considering these problems repeats, but it seems that the GMAT folks are counting one of them as a new problem. Take a look and make up your own mind.
| 1st edition | Unique feature | 2nd edition | Unique feature |
|---|---|---|---|
| PS #78 | "The temperature…" "temperature" |
PS #77 | "Temperatures..." "temperatures" |
| PS #141 | Wrong answer choice (E) is pi/1 | PS #141 | Wrong answer choice (E) is pi/2 |
| PS #175 | Describes a square "countertop" with "tiled" and "untiled" portions | PS #175 | Describes a square "plaque" with "brass" and "wooden" portions |
The GMAT folks also corrected a typo or two.
Minor Trends...
A few minor trends are worth noting, although these trends do not necessarily imply similar shifts on the GMAT itself.
The distribution of topics changed very slightly overall. Word Translations and Geometry grew a little, while the other areas shrank a little.
In the continuation of a trend from the 12th edition, there are a couple of new questions involving "decimal functions." These functions take decimal inputs (e.g., 1.6) and output either the nearest larger integer (2) or the nearest smaller integer (1). Be sure to read the instructions carefully on these problems. There are also a few new interesting questions on sequences. Again, the key is to follow the instructions carefully. Use test numbers to ensure that you completely understand the definition of the sequence.
The meaning of each of these micro-trends is debatable. For instance, since the first editions of these review books were 100% composed of problems drawn from the 10th edition of the main OG (which was also the source of most of the problems in the 11th edition), the GMAT folks could simply be adjusting a previous imbalance. Or there might not be much meaning at all to these particular shifts in topic proportions. Do not draw grand conclusions!
Other Observations
We noted that one Quant problem has been repeated "out of order." The same thing happened with one problem in the Verbal guide.
Data Sufficiency #116 in the 1st edition is actually #31 in the 2nd edition, jumping backward over many intervening problems that exist in both books. Every other repeater that we’ve seen in the Quant Review obeys the implied order of difficulty. That is, if Problem X is before Problem Y in the 1st edition and both survive, then X is before Y in the 2nd edition—except in this case. We don’t know why this happened. The original order of difficulty might have contained this one placement error, and/or the GMAT folks may have placed the problem incorrectly in the 2nd edition.
Note that the issue wouldn’t be "more data." All these problems are retired from the GMAT. In fact, their difficulties would have been measured and set in stone during the experimental phase, prior to active service on the exam. By the way, the transition from the 11th to the 12th presented no such anomalies: all the repeaters kept their relative places in line.
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