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: 17.40b

Answer

There is not sufficient evidence to support the claim that the mean is different from 31,500 pounds.

Work Step by Step

Mean = $\frac{33190+31860+...+28730+31920}{20}$ = 30841 z = $\frac{x-u}{o/\sqrt n}$ = $\frac{30841-31500}{3000/\sqrt 20}$ = -0.98 P = P(Z < -0.98) = 2P(Z < -0.98) = 2(.1635) = .3270
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