Statistics: Informed Decisions Using Data (4th Edition)

Published by Pearson
ISBN 10: 0321757270
ISBN 13: 978-0-32175-727-2

Chapter 7 - Review - Test - Page 395: 9b

Answer

$P(X\lt60)=0.0062$

Work Step by Step

$μ_X=np=500\times0.16=80$ $σ_X=\sqrt {np(1-p)}=\sqrt {500\times0.16(1-0.16)}=8.20$ $P(X\lt60)=P(X\leq59)$ Let's find the z-scores for 59.5 $z=\frac{X-µ_X}{σ_X}=\frac{59.5-80}{8.20}=-2.5$ According to Table V, the area of the standard normal curve to the left of z-score equal to -2.5 is 0.0062.
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