GMAT Tip: Tackling Data-Sufficiency Questions

Photograph by Andersen Ross

This tip on improving your GMAT score was provided by Brian Galvin at Veritas Prep.

Data-sufficiency questions on the GMAT present a scenario and pose a question. They then present two statements of fact, asking test-takers to determine which of the statements, alone or in combination, are sufficient to answer the question. Arguably the most telling of the answer choices is C, which reads:

(C) BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient;

The “NEITHER statement ALONE is sufficient” clause is the one worth rereading, at least now. (On test day, you should know these choices cold and not have to even think about them.) That clause can give you some real insight into how the game is played on Data Sufficiency—the question type is about managing your resources and leveraging all your assets. Human nature is to want to use all available information when making a decision, but answer choice C is written precisely so that you don’t always get to use both statements. If one statement alone is sufficient, you cannot use both. And to better understand what that can mean for you, consider this sample question.

If x represents the number of children on a school bus, what is the value of x?

1. x2 = 36
2. x > 0

Clearly both statements together are sufficient to answer this question. The first statement tells you that x could be 6 or -6, and statement 2 tells you that it has to be the positive one. But remember choice C’s ever-important caveat: ”but NEITHER statement ALONE is sufficient.” This question really comes down to leveraging your resources, and the question stem—albeit more in the form of a riddle—already tells you that x cannot be negative: You can’t have -6 kids on a bus. Therefore the first statement is sufficient alone, even though many would race through this question to “just get to the math,” and others simply prefer having all available pieces of information.

Choice C is written precisely to ensure that if one statement alone is sufficient you have to use it alone. So while in life we tend to ask for and appreciate the second opinion, on the GMAT you need to be stingy with the information you use—only use what you need in order to answer the question. Try to get the most possible value out of each statement. With Data Sufficiency, as with business, it pays to be value-conscious.

Brian Galvin has studied the GMAT full time since 2006 as the director of academic programs for Veritas Prep. He received a Masters in Education from the University of Michigan and is the proud owner of a 99th percentile GMAT score.

For more GMAT advice from Veritas Prep, read “GMAT Data Sufficiency Mastery”

Before it's here, it's on the Bloomberg Terminal.