15.32 A company has test-marketed three new types of soup in selected stores over a period of 1 year. The following table records sales achieved (in thousands of dollars) for each of the three soups in each quarter of the year.

Soup Quarter A B C 1 47 57 65 2 63 63 76 3 79 67 54 4 52 50 49

a. Prepare the two-way analysis of variance table.

b. Test the null hypothesis that population mean sales are the same for all three types of soup.