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Brian Galvin is the Director of Academic Programs at Veritas Prep, where he oversees all of the company’s GMAT preparation courses.
Data Sufficiency questions, which will comprise about half of your quantitative section, are a format unique to the GMAT. As you become familiar with this unique type of question, you’ll find it challenging, frustrating, confusing, infuriating, but hopefully in the end satisfying as you master the many challenges that these questions present.
In this space, we’ve encouraged you to “think like the testmaker” to better understand how the questions will try to bait you in to making mistakes. Well, the most natural way to think like the testmaker is to actually be the testmaker, and the Data Sufficiency format provides a way for you to do that. To better understand the Data Sufficiency format, try writing a few questions of your own – and they don’t need to necessarily be about math. If you write them about trivia, pop culture, sports, history, or any other topic of interest and expertise, you can get a feel for how the math-expert GMAT writers will try to use the format to trick you in to incorrect answers.
The Data Sufficiency format lends itself nicely to a few common traps, including:
You think you have more information than you really do, and select an answer that is actually insufficient
You don’t think you have enough information when you really do, and you fail to select an answer that is sufficient
You incorporate your knowledge of statement (1) alone in to your reading of statement (2), and mistakenly find (2) to be sufficient alone, when in fact it requires the information from (1)
To recreate these traps, try writing a question about a topic on which you are an expert, so that you can either withhold just enough information to make it tricky, or provide just enough information that it won’t look to be enough. By creating these traps yourself, you’ll likely be more adept at looking for them on test questions. Consider the following example:
Who is this United States President?
(1) He took office after 1900
(2) He has the same first and last name as his father
The solution? Well, the (devilishly clever) author of the question wants you to think that statement (2) narrows you down to John Quincy Adams and George W. Bush – the only two presidents whose fathers were also presidents, and who each had the same first and last name. When combined with statement (1), that would lead you to answer C – John Quincy Adams was president before 1900, so he would be eliminated. Upon a closer read, however, notice that statement (2) doesn’t stipulate that the father must have been a president himself. That being the case, Barack Obama, whose father is also named Barack Obama, would also qualify, and the correct answer is E.
In writing this question, the author may have trapped you in to making an assumption regarding statement (2) that would have led you to think you had more information than you did – a very common GMAT device. Because you were thinking along the lines of “US Presidents”, you may have transferred that assumption to each element of the question, much like you’ll be inclined to make that assumption regarding numbers being integers or having positive values.
They say that you don’t know a man until you’ve walked a mile in his shoes, and if that holds you may not thoroughly know how the GMAT is written as well as you would if you wrote a few questions yourself. If you try to write a few questions of your own, you’ll likely find that thinking like the test maker allows you to better anticipate the traps that the GMAT will set for you, and you may learn to love the Data Sufficiency format, after all.
Read more GMAT advice on the Veritas Prep blog. Ready to sign up for a GMAT course? Enroll through GMAT Club and save up to $180 (use discount code GMATC10)!
