The number of cars sold annually by used car dealers is normally distributed with a standard deviation
of 15. A random sample of 15 car dealers was taken, and the number of cars they sold are:
79, 43, 58, 66, 101, 63, 79, 33, 58, 71, 60, 101, 74, 55, 88
a. Compute the 99% confidence interval estimate of the population mean.