Tuddenham and Snyder obtained the following results for 66 California boys at ages 6 and 18 (the scatter diagram is football-shaped):
average height at 6≈3 feet 10 inches, SD≈1.7 inches
average height at 18≈5 feet 10 inches, SD≈2.5 inches, r≈0.80
a) Find the r.m.s. error for the regression prediction of height at 18 from height at 6.
b) Find the r.m.s. error for the regression prediction of height at 6 from height at 18.