SAT Mathematics Practice Test 4

The standard deviation is a measure of how far the data set values are from the mean. In the data set for City A, the large majority of the data are in three of the five possible values, which are the three values closest to the mean. In the data set for City B, the data are more spreadout, with many values at the minimum and maximum values. Therefore, by observation, the data for City B have a larger standard deviation.
Alternatively, one can calculate the mean and visually inspect the difference between the data values and the mean. For City A the mean is

1,655

21

≈78.8 and for City B the mean is

1.637

21

≈78.0 The data for City A are closely clustered near 79, which indicates a small standard deviation. The data for City B are spread out away from 78, which indicates a larger standard deviation.
Choices A, C, and D are incorrect and may be the result of misconceptions about the standard deviation.