Advertising expenses are a significant component of the cost of goods sold. Listed below is a frequency distribution showing the advertising expenditures for 60 manufacturing companies located in the Southwest. Estimate the mean and the standard deviation of advertising expenses.

Advertising Expenditure ($ millions) Number of Companies

25 up to 35............ 5

35 up to 45............ 10

45 up to 55............ 21

55 up to 65............ 16

65 up to 75............ 8

Total...................... 60