15.33 A diet soda manufacturer wants to compare the effects on sales of three can colors—red, yellow, and blue. Four regions are selected for the test, and three stores are randomly chosen from each region, each to display one color of cans. The accompanying table shows sales (in tens of cans) at the end of the experimental period.

Can Color Region Red Yellow Blue East 47 52 60 South 56 54 52 Midwest 49 63 55 West 41 44 48

a. Prepare the appropriate analysis of variance table.

b. Test the null hypothesis that population mean sales are the same for each can color.