Consider this population data set: 4, 6, 7, 11, 12, 18, 26, 23, 14, 31, 22, and 12. The values 11, 31, 22, and 12 constitute a random sample drawn from the data set. The sample mean is more than the population mean by

The population mean is the sum of the 12 data set values divided by 12:

4 + 6 + 7 + 11 + 12 + 18 + 26 + 23 + 14 + 31 + 22 + 12 = 186.

Therefore the population mean = 186/12 = 15.5.

The sample mean is the sum of the 4 sample values divided by 4:

11 + 31 + 22 + 12 = 76.

Therefore the sample mean = 76/4 = 19.

The sample mean is more than the population mean by 19 - 15.5 = 3.5.