Which data set has the smallest standard deviation?

A. 7, 8, 89, 1005, 23400, 5, 3

B. 1000, 1001, 1002, 1000, 1001, 1001

C. 55, 90, 34, 78, 15, 20, 19

D. 1, 9, 120, 9, 1, 1, 9

The answer would be B.

Standard deviation basically measures how spread out the values are. Without solving, you can easily tell which one among your choices have a smaller deviation. The closer the values are to each other the smaller the standard deviation. The values of choice B are the closest together, so you can assume that they have the smallest standard deviation.