For a study of University of Georgia female athletes, the prediction equation relating y = total body weight (in pounds) to x1 = height (in inches) and x2 = percent body fat is = -121 + 3.50 x1 + 1.35x2.
a. Find the predicted total body weight for a female athlete at the mean values of 66 and 18 for x1 and x2.
b. An athlete with x1 = 66 and x2 = 18 has actual weight y = 115 pounds. Find the residual, and interpret it.