Data Sufficiency Yes No Questions

Note that this differentiation is one that we make. When you take the test, you will not be told whether a problem is a yes/no or value question. However, the ability to differentiate between these two question types is an extremely valuable tool in mastering data sufficiency.

Yes/No Questions

Yes/No Questions ask a question that needs to be answered with "yes" or "no" (hence the name of the question type). In this problem type, for a statement to be sufficient, the information it provides must enable you to answer definitively the question with "yes" or "no" every time. In other words, a statement is not sufficient if you can answer "no" or "yes." Note that even if your answer is "no," as long as the information provided in the statement is sufficient to answer "no" every time, the statement is sufficient. Consider the following example: (Note that a real test question would never be this easy. However, this question is constructed to help elucidate the problem type and format.)

The difficulty with these question patterns is that it can be difficult to get your mind around whether or not a statement is sufficient, especially if you’re able to determine from the given statement that the answer to the question would actually be “no.” Yet, the very fact that you were able to determine that the answer to the question would be “no” means that you do in fact have enough information to answer the question. In that case, the statement is question would be sufficient.

Question:

If x is a positive integer, is x > 15?

1- x > 10

2- x < 14

Explanation:

The Correct Answer: B

• n order for a statement to be sufficient, it must definitively answer the question (i.e., it must definitively indicate whether x > 15?) For sufficiency to exist, the information in the statement must allow you to answer the question with the same answer every time (either "yes" or "no). The key is not whether the answer is "yes" or "no", but whether the information allows you to answer the same way each time.
• Statement (1) indicates that x > 10. So, x could be 11, 12, 13, 14, 15, 16, 17...
• Since x could be 11, in which case it would not be greater than 15 and the answer to the origial question would be "no", or x could be 17, in which case it would be greater than 15 and the answer to the original question would be "yes", Statement (1) is NOT SUFFICIENT.
• Statement (2) indicates that x < 14. So, x could be 13, 12, 11, 10, 9... Since all the possible values of x permissible by Statement (2) allow you to answer "no" to the question, Statement (2) is SUFFICIENT.