58 Suppose you fit the quadratic model E(y) = b0 + b1 x + b2 x2 to a set of n = 20 data points and find that R2 = .91, SSyy = 29.94, and SSE = 2.63.

a. Is there sufficient evidence to indicate that the model contributes information relevant to predicting y ? Test using a = .05.

b. What null and alternative hypotheses would you test to determine whether upward curvature exists?

c. What null and alternative hypotheses would you test to determine whether downward curvature exists?