In Exercise 15-47, you were asked to use best subsets stepwise regression to establish the relationship between body fat and the independent variables weight, abdomen circumference, and thigh circumference based on data in the file Bodyfat. This is an extension of that exercise.

a. Construct an estimate of the regression equation using the same variables.

b. Produce the appropriate residual plots to determine if the linear function is the appropriate regression function for this data set.

c. Use a residual plot to determine if the residuals have a constant variance.

d. Produce the appropriate residual plot to determine if the residuals are independent. Assume the data were extracted in the order listed.

e. Construct a probability plot to determine if the error terms are normally distributed.