Statistics: Informed Decisions Using Data (4th Edition)

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

Chapter 7 - Section 7.4 - Assess Your Understanding - Applying the Concepts - Page 392: 24c

Answer

Yes, I would be surprised because it is an unusual event.

Work Step by Step

$μ_X=np=300\times0.267=80.1$ $σ_X=\sqrt {np(1-p)}=\sqrt {300\times0.267(1-0.267)}=7.66$ $P(X\gt100)=P(X\geq101)$ Let's find the z-score for 100.5: $z=\frac{X-μ}{σ}=\frac{100.5-80.1}{7.66}=2.66$ According to Table V, the area of the standard normal curve to the left of z-score equal to 2.66 is 0.9961 But, we want the area of the standard normal curve to the right (more than 100) of z-score equal to 2.66: $1-0.9961=0.0039$ $P(X\gt100)=0.0039\lt0.05$. It is an unusual event.
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