Elementary Statistics: A Step-by-Step Approach with Formula Card 9th Edition

Published by McGraw-Hill Education
ISBN 10: 0078136334
ISBN 13: 978-0-07813-633-7

Chapter 6 - The Normal Distribution - Review Exercises - Section 6-4 - Page 363: 22



Work Step by Step

Given $p=0.26, n=60$ we have $np=15.6, n(1-p)=44.4$ both large enough to allow normal approximation to the binomial distribution. $\mu=np=15.6, \sigma=\sqrt {np(1-p)}=3.4$ Use $X=19.5, z=\frac{19.5-15.6}{3.4}=1.147$ The probability above this z-score is 0.126
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