The numbers of courses taught per semester by a random sample of university professors are shown in the histogram. Make a frequency distribution for the data. Then use the table to estimate the sample mean and the sample standard deviation of the data set. Number of professors 25 20- 15- 10- 4 19 Make a frequency distribution for the data. f X 1 2 34 1 2 23 3 15 4 Number of courses taught per semester 2