79. Let y  sales at a fast-food outlet ($1000 s), x1 

number of competing outlets within a 1-mile radius, x2  population within a 1-mile radius (1000 s of people), and x3 be an indicator variable that equals 1 if the outlet has a drive-up window and 0 otherwise.

Suppose that the true regression model is

a. What is the mean value of sales when the number of competing outlets is 2, there are 8000 people within a 1-mile radius, and the outlet has a drive-up window?

b. What is the mean value of sales for an outlet without a drive-up window that has three com-

Y  10.00  1.2x1  6.8x2  15.3x3  e peting outlets and 5000 people within a 1-mile radius?

c. Interpret b3.