The ordered array below represents the number of cargo manifests approved by customs inspectors of the Port of New York in a sample of 35 days:

16, 17, 18, 18, 19, 20, 20, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23,

24, 24, 24, 25, 25, 26, 26, 26, 27, 28, 28, 29, 29, 31, 31, 32, 32

For this sample, the sum of the observations is 838, the sum of the squares of the observations is 20,684, and the sum of the squared differences between each observation and the mean is 619.89.

a) What is the arithmetic mean of the customs data?

b) What is the variance of the customs data?

c) What is the standard deviation of the customs data?

d) What is the coefficient of variation of the customs data?