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. 25- 21 20 20- 48 15- 10- 5- Number of courses taught per semester 1. 2 20 3 21 4 18 The sample mean is x= (Round to one decimal place as needed.) The sample standard deviation is s=. (Round to one decimal place as needed.) Number of professors