Difficulty Level of GMAC GMAT Material

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I'm often asked how hard the questions in The Official Guide are. I never had a specific answer until now.

I just realized that I can use data that I've already created and collected to address the question. I've long had a database of all the Official Guide questions, indexed by difficulty level and content area. (Lists of questions, categorized in both ways, are included in my Guide to the Official Guide.)

A brief overview: I rate every question with a number between 3 and 7. 3 is easiest, 7 is hardest. I have a general idea of the score ranges represented by each one: for instance, 5 runs from 500 to 620, and 7 runs from 720 to 800. For some reason, it never occurred to me that I could use an average of those ratings to compare question sets.

What They Mean

Let me be clear about how to interpret these. When I say that a question is "600-level," I mean that approximately 50% of those who get a 600 would get it right, and 50% would get it wrong. If you can get it right under timed conditions, you're probably set to score higher than 600. If not, you probably aren't.

So, when I say that a set of questions is "700-level," I mean this: If you have the skills and strategy required to get exactly a 700, and do those questions under timed conditions, you will get about half of them right. (Probably a little better, because sometimes you'll guess randomly and get it right anyway.)

Let's say that you took the test before and got a 550. Further, that you're aiming for a 650. That doesn't mean that you should look for 650-level questions. If you got a 550, that means you're missing half the questions you saw at the 550 level. It's more important that you shore up your problems in the 550-600 level than focus on tougher items. If you focus solely on 650 questions and above, you may have the same problems on 550-600-level questions, and never see those tougher problems.

The Scores: GMAT Orange Book

Here's how I rate the questions in the diagnostic test at the front of the book:

  • Problem Solving (PS): 580
  • Data Sufficiency (DS): 550
Sample questions (the meat of the book):
  • PS: 560
  • DS: 560
More specifically, here are the scores for each segment of 50 questions:
  • PS 1-50: 480
  • PS 51-100: 520
  • PS 101-150: 560
  • PS 151-200: 610
  • PS 201-249: 670

  • DS 1-50: 480
  • DS 51-100: 530
  • DS 101-155: 660
If you've worked all the way through the book, this should ring true: the last few dozen questions in each section are much harder than everything that precedes them.

The Scores: GMAT Green Book Here are the same measurements for the Supplemental Math Review:

  • PS: 540
  • DS: 540
Split into segments:
  • PS 1-60: 490
  • PS 61-120: 560
  • PS 121-176: 600

  • DS 1-40: 480
  • DS 41-80: 570
  • DS 81-118: 580
Again, this passes a smell test. There isn't a huge difference between the Green and Orange books, but the Supplemental Guide is not quite as hard, and doesn't have the same number of notably difficult questions.

My Questions

In the next few week or so, I'll do the same calculations on my sets of practice questions. In general, I've discovered that my "Challenge" sets average in the 650-670 range, and that my "Fundamentals" sets are between 450-500.

Other Test-Prep Providers

When a book says it contains a lot of difficult material, be skeptical. Most mass-market books don't. Or, they have hard questions that aren't very test like. Even Kaplan 800, with its attention-getting name, would probably average about 650 on this scale.

Verbal Questions

I haven't done the same calculations for verbal questions, and I'm not entirely sure that I could. It's one thing to see a question and recognize that it's easy or hard; it's another to distinguish between a 600 and a 650. I guess you'll have to settle for my Quantitative estimates for now.



About the author: Jeff Sackmann has written many GMAT preparation books, including the popular Total GMAT Math, Total GMAT Verbal, and GMAT 111. He has also created explanations for problems in The Official Guide, as well as 1,800 practice GMAT math questions.

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