Elementary Statistics: Picturing the World (6th Edition)

Published by Pearson
ISBN 10: 0-32191-121-0
ISBN 13: 978-0-32191-121-6

Chapter 5 - Normal Probability Distributions - Section 5.2 Normal Distributions: Finding Probabilities - Exercises - Page 249: 7

Answer

a) $P(x < 66) = 0.1210$ b) $P(66 < x <72)$ = 0.6949 c) $P(x > 72) = 0.1841$ d) No event here is unusual.

Work Step by Step

a) $P(x < 66)$ $z = \frac{66-69.4}{2.9} \approx -1.17$ $P( z 72)$ $P(z > 0.90) = 1-0.8159 = 0.1841$ Therefore $P(x > 72) = 0.1841$ d) No event here is unusual. We can infer this because the z score of each value is less than 2. Also, the probability of getting each value is above 0.05.
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