The mean number of credits earned by students is claimed to be 30.0. A random sample is taken to test if the mean is different. The sample has , s = 2.1, and n = 40. Use this data to solve problems 7 through 11.
The stem and leaf plot below shows the running times in a 400 m run for a random sample of 19 runners. 6|0 represents 60 seconds. Use this data for questions 18 through 21.