The concept of standard deviation is often used in data sufficiency questions on the GMAT. You will not need to calculate standard deviation, but you must understand what it is and how it is used.

Below are several examples of how to answer data sufficiency questions that involve standard deviation.

## Example

Set W consists of 6 values. What is the standard deviation of set W?

(1) The mean of the set is 10.

(2) The range of the set is 10.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 statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.