11.13 A pet food company has a business objective of expanding its product line beyond its current kidney- and shrimp-based cat foods. The company developed two new products, one based on chicken liver and the other based on salmon. The company con- ducted an experiment to compare the two new products with its two existing ones, as well as a generic beef-based product sold at a supermarket chain.

For the experiment, a sample of 50 cats from the population at a local animal shelter was selected. Ten cats were randomly assigned to each of the five products being tested. Each of the cats was then presented with 3 ounces of the selected food in a dish at feeding time. The researchers defined the variable to be measured as the number of ounces of food that the cat consumed within a 10-minute time interval that began when the filled dish was presented. The results for this experiment are summarized in the table at top right and stored in CatFood .

1. At the 0.05 level of significance, is there evidence of a difference in the mean amount of food eaten among the various products?
2. If appropriate, determine which products appear to differ significantly in the mean amount of food eaten.
3. At the 0.05 level of significance, is there evidence of a difference in the variation in the amount of food eaten among the various products?