:12c. Solution.  130 pounds is 0.5 SD's above average, so the
heights of those who weigh 130 pounds is 0.6 x 0.5 = 0.3 SD's
above average. The average height of the 130 pounders is 68 +
(0.3 X 3) = 68.9 inches.  The SD of these heights is the rms
error of estimating height from weight, or 0.8 x 3 = 2.4 inches. 
90th percentile corresponds to a tabular value of 80%, so z =
1.30. Since 68.9 + (1.30 x 3) = 68.9 + 3.9 = 72.8 inches.  So
the closest of the available answers is 73 inches.