GMAT Data Sufficiency Sample Questions

Defining the margins of problems

GMAT DATA SUFFICIENCY

GMAT Data Sufficiency is a very unique question type among GMAT questions and test prep in overall. Unlike a typical problem where you have to directly answer a question, a data sufficiency problem requires that you determine whether a question can be conclusively answered by analyzing two pieces of evidence, or statements, that are 100% true (re-read the underlined to save yourself a lot of time in the next weeks and months as you prepare), first separately, then combined.

Consider the example below

Data Sufficiency sample problem

Is the positive integer x even?

(1) When you divide the integer x by 4, the remainder is not 0.

(2) When you divide the integer x by 2, the remainder is not 0.

A – STATEMENT (1) ALONE is sufficient, but STATEMENT (2) alone is not sufficient.

B – STATEMENT (2) ALONE is sufficient, but STATEMENT (1) alone is not sufficient.

C – BOTH STATEMENTS TOGETHER are sufficient, but NEITHER ALONE is sufficient.

D – EACH STATEMENT ALONE is sufficient.

E – NEITHER STATEMENT ALONE NOR TOGETHER are sufficient.

Show answer

The correct answer is B.
According to statement (1), when you divide the integer x by 4, the remainder is not 0. This is inconclusive because:
I can identify integers that are odd that satisfy that statement, but also even integers that satisfy the statement. For example:
(i) when the ODD integer 15 is divided by 4, the remainder is not 0.
(ii) when the EVEN integer 6 is divided by 4, the remainder is not 0.
For a statement to be declared sufficient, it must allow us to conclusively say YES x is surely even, or NO x is surely not even.
Statement (2) is conclusive because any even integer is divisible by 2.