GMAT Gurus Speak Out: Don’t Break Data Sufficiency Rules

Data Sufficiency statements can’t be altered. Every so often when I am tutoring a student, he or she will change up the rules of data sufficiency. I’ve seen it before with misunderstanding a “yes/no” data sufficiency question (by erroneously thinking an answer of “always no” means “not sufficient.”)

However, more than once in the last few weeks, students are creating a new rule that is a score killer. They are not accepting the numbered statements as absolute truths.

The GMAT test taker’s job is to assess the sufficiency of the numbered statements. It is NOT the test taker’s job to disprove the numbered statements. Those statements cannot be changed because they are true.

How is this done? Sometimes a test taker picks numbers which violate the numbered statements. Consequently, he or she mistakenly determines sufficiency based on that instead of the actual question stem.

Here is an example:

Is x>0?

Statement 1: x+12>10

The student might erroneously plug in a number that would violate “x+12>10” and think “well if x is 20, x+12>10, but if x is -4, then x+12 is not greater than 10. Therefore this is not sufficient.” But the overall question is not “Is x+12>10.” That is a statement that has to be accepted as fact when determining the sufficiency of the real overall question of “Is x>0?” The only numbers that can be tested for statement 1 are those that fit within the parameters of the statement (x>-2).

It is very important to know very early in your data sufficiency studies that Statements 1 and 2 are facts! They are always true. These statements cannot be disproved, and numbers that violate what the statements tell you are not to be used. If you “disprove” one of the numbered statements, you are asking for trouble!

So, remember to accept data sufficiency statements as absolute truths and hopefully this will help keep your GMAT score up!

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Steve Odabashian received his BA in Economics from the University of Virginia and then went on to receive his JD at Villanova. He has worked in Tokyo as a foreign attorney, done pro bono work for the Committee of Seventy in several Philadelphia elections, and he is a well known pianist and comic entertainer in Philadelphia. Steve has been teaching for Veritas Prep since 2004.