A consumer organization wants to estimate the actual tread wear index of a brand name of tires that claims graded "200" on the sidewall of the tire. A random sample of n=16 indicates a sample mean tread wear index of 197.7 and a sample standard deviation of 29.3.
a. Supposing that the population of tread wear indexes is normally distributed, construct a 95% confidence interval estimate of the population mean tread wear index for these tires.