Elementary Statistics: A Step-by-Step Approach with Formula Card 9th Edition

Published by McGraw-Hill Education
ISBN 10: 0078136334
ISBN 13: 978-0-07813-633-7

Chapter 8 - Hypothesis Testing - Review Exercises - Section 8-6 - Page 482: 20

Answer

No. Yes. See explanations.

Work Step by Step

Given $\mu=35, \sigma= 3, n=36, \bar X=33.5$ a. State the hypotheses and identify the claim. $H_o: \mu=35$ $H_a: \mu\ne 35$ (claim, two tail test) b. Find the critical value(s). $\alpha/2=0.05, |z_c|=1.645$ c. Compute the test value. $z=\frac{33.5-35}{3/\sqrt {36}}=-3$ d. Make the decision. Since $z\lt-1.645$, we should reject the null hypothesis. e. Summarize the results. At α= 0.10. the tires are not properly inflated. For $c=0.6$, we have $z_c=1.645$ and the margin of error is $E=1.645\times\frac{3}{\sqrt {36}}=0.82$ and the interval is $(33.5-0.82, 33.5+0.82)$ which gives $32.7\leq \mu \leq 34.3$ and clearly the mean $\mu=35$ is outside the range and we should reject the null hypothesis. The results from the two calculations agree with each other.
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