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Chapter 11: Q. 122 (page 669)

Consumers may be interested in whether the cost of a particular calculator varies from store to store. Based on surveying 43 stores, which yielded a sample mean of \(84 and a sample standard deviation of \)12, test the claim that the standard deviation is greater than $15.

Short Answer

Expert verified

Taking 伪=0.05, we can see that p>伪. This means that we cannot reject null hypothesis.

There is insufficient evidence to conclude that the standard deviation is greater than 15.

Step by step solution

01

Given Information

We want to test these hypotheses:

H0:蟽鈮�15

H1:蟽>15

We are given a sample from n=43stores with standard deviation s=12.

02

Explanation

This means that the number of degrees of freedom is

n-1=43-1=21

We are using 蠂2distribution. The test statistic is given by:

蠂2=42路s2152=26.88

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Most popular questions from this chapter

The number of births per woman in China is 1.6down from 5.91in 1966. This fertility rate has been attributed to the law passed in 1979restricting births to one per woman. Suppose that a group of students studied whether or not the standard deviation of births per woman was greater than 0.75. They asked 50women across China the number of births they had had. The results are shown in Table. Does the students鈥� survey indicate that the standard deviation is greater than 0.75?

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From the population of students, do the nights for the highest number of students doing the majority of their homework occur with equal frequencies during a week? What type of hypothesis test should you use?
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