Consider the following data, which result from an experiment to determine the effect of x = test time in hours at a particular temperature on y = change in oil viscosity:

(a) Fit a second-order polynomial to the data.
(b) Test for significance of regression using a = 0.05.
(c) Test the hypothesis that B11 = 0 using a = 0.05.
(d) Compute the residuals from part (a) and use them to evaluate model adequacy.

-1.42 -2.43 -1.89 -1.39 -1.55 25 1.25 50 .75 1.00 -7.89 -7.89 -3.15 -4.05 -5.15 -6.43 1.50 1.75 2.25 2.50 2.00