The number of pages per book on a bookshelf is normally distributed with mean 248 pages and standard deviation 21
pages. Using the empirical rule, what is the probability that a randomly selected book has less than 206 pages?
SOLUTION
Using Z-score =
(Given score - Mean) / Standard Deviation
Z- score = ( 206 - 248 ) / 21 = -2
P ( less than -2 ) = 0. 002275 x 100 % = 0. 2275 % = 0 . 2 % ( 1 decimal place)