Problem 11.11 The following data come from an experiment to determine the relation between Y, the shear strength (psi) of a rubber compound, and X, the cure temperature (oF).

(a) Draw the scatter plot to see if the simple linear regression model is appropriate.

(b) Fit the quadratic polynomial Model (Y = shear strength |X1 = x, X2 = x2) to these data.

(c) Draw the graph of the fitted polynomial on the same set of axes you used for the scatter plot.

(d) Test the hypothesis that βˆ2 = 0.

(e) Check the assumptions of the model by (1) graphing the studentized residual plot and (2) graphing the normal probability plot of the studentized residuals. y x 770 280 800 284 840 292 810 295 735 298 640 305 590 308 560 315