The professor swims. Return to the swimming data in Exercise 15.9.

(a) Verify the equation given for the least-squares line in that exercise.

(b) Suppose you were told only that the pulse rate was 152. You now want to predict swimming time. Find the equation of the least-squares regression line that is appropriate for this purpose. What is your prediction?

(c) The two lines in

(a) and

(b) are different. Explain clearly why there are two different regression lines.