A college math professor has office hours from 9:00 am to 10:30 am daily. A random sample of waiting times to see the professor (in minutes) is 10, 12, 20, 15, 17, 10, 30, 28, 35, 28, 19, 27, 25, 22, 33, 37, 14, 21, 20, 23. Assuming find the 95% confidence interval for the population mean.