The average precipitation for the first 7 months of the year is 19.32 inches with a standard deviati

The average precipitation for the first 7 months of the year is 19.32 inches with a standard deviation of 2.4 inches. Assume that the average precipitation is normally distributed.

a. What is the probability that a randomly selected year will have precipitation greater than 18 inches for the first 7 months?

b. What is the average precipitation of 5 randomly selected years for the first 7 months?

c. What is the probability of 5 randomly selected years will have an average precipitation greater than 18 inches for the first 7 months?

For a. we set up our z-score for:
P(X>18) = 0.7088

b. We assume the average precipitation of 5 randomly selected years for the first 7 months is the population mean μ = 19.32

c. P(X > 18 with n = 5) = 0.8907