An article entitled “A Method for Improving the Accuracy of Polynomial Regression Analysis’’ in the Journal of Quality Technology reported the followingdata on y = ultimate shear strength of a rubber...

An article entitled “A Method for Improving the Accuracy of Polynomial Regression Analysis’’ in the
Journal of Quality Technology
 reported the followingdata on
y
= ultimate shear strength of a rubber compound(psi) and
x
= cure temperature (°F).

 (a) Fit a second-order polynomial to these data.

(b) Test for significance of regression using α = 0.05.

(c) Test the hypothesis that β₁₁= 0 using α = 0.05.

(d) Compute the residuals from part (a) and use them to evaluate model adequacy.