For the Georgia Student Survey file on the text CD, the prediction equation relating y = college GPA to x1 = high school GPA and x2 = study time (hours per day), is ŷ = 1.13 + 0.643x1 + 0.0078x2.
a. Find the predicted college GPA of a student who has a high school GPA of 3.5 and who studies three hours a day.
b. For students with fixed study time, what is the change in predicted college GPA when high school GPA increases from 3.0 to 4.0?
a. ŷ = 1.13 + 0.643 x1 + 0.0078 x2 = 1.13 + 0.643(3.5) + 0.0078(3) = 3.41
b. For a fixed study time, the change in predicted college GPA is 0.64 (the slope) as high school GPA goes from 3.0 to 4.0.