In Problem 12.6 on page 424, the owner of a moving company wanted to predict labor hours based on the number of cubic feet moved. The data are stored in Moving.
a. Construct a 95% confidence interval estimate of the mean labor hours for all moves of 500 cubic feet.
b. Construct a 95% prediction interval of the labor hours of an individual move that has 500 cubic feet.
c. Why is the interval in (a) narrower than the interval in (b)?