Recall the small bookstore we saw in Exercise 9.

The regression line is:

Sales = 8.10 + 0.9134 Number of Sales People Working and the assumptions and conditions for regression are met.

Calculations with technology find that se = 1.477.

a) Find the predicted sales on a day with 500 employees working.

b) Find a 95% prediction interval for the sales on a day with 500 employees working.

c) Are these predictions likely to be useful? Explain.