13.65 Use the data and the answers found in Exercise 13.59 (p. 725) to make the following estimates.

a. Give a point estimate for the mean time required to commute 4 miles.

b. Give a 90% confidence interval for the mean travel time required to commute 4 miles.

c. Give a 90% prediction interval for the travel time required for one person to commute the 4 miles.

d. Answer parts a–c for x  9.