Suppose you fit the interaction model y = b0 + b1x1 + b2x2 + b3x1x2 + e to n = 32 data points and obtain the following results: SSyy = 479 SSE = 21 bn 3 = 10 sbn3 = 4

a. Find R2 and interpret its value.

b. Is the model adequate for predicting y? Test at a = .05.

c. Use a graph to explain the contribution of the x1x2 term to the model.

d. Is there evidence that x1 and x2 interact? Test at a = .05.