The president of Blitz Sales Enterprises sells kitchen products through cable television infomercials. He gathered data from the last 15 weeks of sales to determine the relationship between sales and the number of infomercials. Infomercials Sales
20 3.2
15 2.6
25 3.4
10 1.8
18 2.2
18 2.4
15 2.4
12 1.5
22 2.5
15 2.4
25 3
16 2.7
12 2
20 2.6
25 2.8

Required:
a. Determine the regression equation. Are the sales predictable from the number of commercials?
b. Determine the residuals and plot a histogram. Does the normality assumption seem reasonable?