The Basic Practice of Statistics 7th Edition

Published by W. H. Freeman
ISBN 10: 146414253X
ISBN 13: 978-1-46414-253-6

Chapter 17 - Tests of Significance: The Basics - Chapter 17 Exercises - Page 413: 17.40a

Answer

There is sufficient evidence to support the claim that the mean is different from 32,500 pounds.

Work Step by Step

We find: Mean = $\frac{33190+31860+...+28730+31920}{20}$ = 30841 z = $\frac{x-u}{o/\sqrt n}$ = $\frac{30841-32500}{3000/\sqrt 20}$ = -2.47 P = P(Z < -2.47) = 2P(Z < -2.47) = 2(.0068) = .0136
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