The MINITAB output given in Table 9.26 resulted from fitting the multiple regression model relating ???? to the explanatory variables ????1,????2, and ????3. Assuming that the assumptions of the model are valid, use the information in Table 9.26 to answer the following questions.

(a) Determine the equation of the fitted model.

(b) Test ????0 ∶ ????1 = ????2 = ????3 = 0 at the ???? = 0.01 level.

(c) Estimate the expected change in ???? for a one unit increase in ????2 when ????1 and ????3 are held fixed.

(d) Test ????0 ∶ ????1 = 0 at the ???? = 0.05 level.

(e) Compute a 95% confidence interval for ????2.