The Data and Story Library website ( a website devoted to applications of statistics) gives a histogram of the ages of a sample of 60 CEOs. We present the data in the form of a frequency distribution below.

Age (Years) Frequency

28– 32............ 1

33– 37............ 3

38– 42............ 3

43– 47............ 13

48– 52............ 14

53– 57............ 12

58– 62............ 9

63– 67............ 1

68– 72............ 3

73– 77............ 1

Calculate the (approximate) sample mean, variance, and standard deviation of these data.