The Iams Company sells dog and cat foods (dry and canned) in countries throughout the world. Suppose that one of the company’s dry dog food products comes in five formulas. One of the ingredients is of particular importance: crude fat. To discover if there is a difference in the average percentage of crude fat among the five formulas and among the production sites, the sample data found in the file titled Iams were obtained.

a. Determine if there is interaction between the five formulas and the plant sites where they are produced. Use the p-value approach and a significance level of 0.025.

b. Given your findings in part

a, determine if there is a difference in the average percentage of crude fat in the five formulas. Use a test-statistic approach with a significance level of 0.025.

c. One important finding will be whether the average percent of crude fat for the “Reduced Fat” formula is equal to the advertised 9%. Conduct a relevant hypothesis test to determine this using a significance level of 0.05.