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: 25a

Answer

$P(X\geq130)=0.0028$

Work Step by Step

55% = 0.55 $μ_X=np=200\times0.55=110$ $σ_X=\sqrt {np(1-p)}=\sqrt {200\times0.55(1-0.55)}=7.04$ Let's find the z-score for 129.5: $z=\frac{X-μ}{σ}=\frac{129.5-110}{7.04}=2.77$ According to Table V, the area of the standard normal curve to the left of z-score equal to 2.77 is 0.9972. But, we want the area of the standard normal curve to the right (at least 130) of z-score equal to 2.77: $1-0.9972=0.0028$
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