Data sufficiency 'gotchas'

Last updated: 3 Mar 2007

There are lots of tricks or 'gotchas' that are used commonly in GMAT data sufficiency questions to catch you out and you need to learn to spot these.

There are too many of these to list in this tutorial and learning these is a case of trying lots of practice questions.

Once you have reviewed 100 or more practice questions you will become very familiar with these 'gotchas' and you should aim not to fall for the same trick twice.

However, there is one 'gotcha' that is worth covering in this tutorial.

The answer can be no

Although the data statements will never contradict one another, they may sometimes lead to a negative answer.

Lots of beginners get caught out by data sufficiency questions where the answer is no, and mark no against the data statement without thinking.

For example

Is x even?

  1. 2x is even
  2. x + 1 is even
  1. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient
  2. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient
  3. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
  4. EACH statement ALONE is sufficient
  5. Statements (1) and (2) TOGETHER are NOT sufficient

You should be able to see that first statement does not answer the question for you. Even if 2x is even, x could still be even or odd. So you can mark statement 1 as 'no'.

The second statement however tells you that x is odd and therefore you know that the answer to the question is no. Be careful here, you may be tempted to mark statement 2 as 'no' but statement 2 has given you enough information to answer the question so you must mark it as 'yes'.

Since the second statement answers the question alone and the first statement does not the answer is B.

Next page: Summary of data sufficiency

You must log in or register to add a comment.

Creative Commons License