Practice GMAT Data Sufficiency Question
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If A and B are integers, is B > A?
 B > 10
 A < 10
Correct Answer: C

Evaluate Statement (1) alone.
 Statement (1) simply says that B > 10. It provides no information about the value of A, making a comparison between B and A impossible.
 If B = 12 and A = 5, then the answer to the question "is B > A?" would be yes. However, if B = 15 and A = 20, then the answer to the question "is B > A?" would be no.
 Since different legitimate values of A and B produce different answers to the question, Statement (1) is NOT SUFFICIENT.
 Note: Some students are thrown off by setting A = 20 or A = 5. You can do this in evaluating whether Statement (1) alone is sufficient since there is nothing in Statement (1) that prevents this. However, A cannot be 20 in evaluating statement 2 because Statement (2) clearly says that A must be less than 10. But, for now we are evaluating Statement (1).

Evaluate Statement (2) alone.
 Statement (2) simply says that A < 10. It provides no information about the value of B, making a comparison between B and A impossible.
 If B = 12 and A = 5, then the answer to the question "is B > A?" would be yes. However, if B = 1 and A = 9, then the answer to the question "is B > A?" would be no.
 Since different legitimate values of A and B produce different answers to the question, Statement (2) is NOT SUFFICIENT.
 Note: Some students are thrown off by setting B = 1 or B = 12. You can do this in evaluating whether Statement (2) alone is sufficient since there is nothing in Statement (2) that prevents this.

Evaluate Statements (1)and (2) together.
 When taking Statements (1) and (2) together, you know:
B > 10 and A < 10  So, you know that B > A. Statements (1) and (2), when taken together, are SUFFICIENT.
 When taking Statements (1) and (2) together, you know:
 Since Statement (1) alone is NOT SUFFICIENT and Statement (2) alone is NOT SUFFICIENT yet Statements (1) and (2), when taken together, are SUFFICIENT, answer C is correct.
Return to the list of practice GMAT data sufficiency questions.