:11. Solution.  Since (160 -168)/28 = -8/28 = -2/7 , a weight
of 160 pounds is 2/7 SD's below average.  Since r x 2/7 = 0.4 x
2/7 =  8/70 = .114, the average height of the 160-pounders is
.114 SD's below the average height of everyone in the study, that
is, 68 - .114 x 2.8 = 68 - .32 = 67.68 = 67.7 1nches.  The
correct choice is 68 inches.