[EX03-040] A marketing firm wished to determine whether the number of television commercials broadcast were linearly correlated with the sales of its product. The data, obtained from each of several cities, are shown in the following table.

City A B C D E F G H I J Commercials, x 12 6 9 15 11 15 8 16 12 6 Sales Units, y 7 5 10 14 12 9 6 11 11 8

a. Draw a scatter diagram.

b. Estimate r.

c. Calculate r.