6.Assume that serum cholesterol levels are normally distributed. We are given that the mean serum cholesterol level of U.S. males aged 20-74 is 211 mg/dL, and that the standard deviation () of that population is 46 mg/dL. You randomly select 16 individuals from that population.

a. Would you use the Z table or t table? Why?

b. What is the probability that an individual of the 16 selected has a cholesterol level greater than 280 mg/dL?

c.What is the probability that a sample mean from a group of 16 has a cholesterol level greater than 280 mg/dL?