:7. The standard score of someone scoring at the 90th percentile
level is 1.3 (see page 156). If someone scores 1.3 SD's above aver age on the LSAT, the regression estimate of his first-year score is
0.6 x 1.3 = .78, or approximately .80. The area under the normal 
curve between -.80 and .80 is about 58%, so the area to the left
of .80 is 58 +(42/2) = 58 + 21 = 79%. So the best estimate of his
percentile rank and of his first-year score is 79%, which is
closest to 80% .