Answer
$91.92\%$.
Work Step by Step
$z=\frac{\text{data item-mean}}{\text{standard deviation}}$.
Hence here: $z=\frac{142-121}{15}=1.4$
Using the table, the percentage of data items in a normal distribution that lie below it: $91.92\%$.
Thinking Mathematically (6th Edition)
by Blitzer, Robert F.
Published by
Pearson
ISBN 10:
0321867327
ISBN 13:
978-0-32186-732-2
Chapter 12 - Statistics - 12.5 Problem Solving with the Normal Distribution - Exercise Set 12.5 - Page 820: 17
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