11.2 Most individuals are aware of the fact that the average annual repair cost for an automobile depends on the age of the automobile. A researcher is interested in finding out whether the variance of the annual repair costs also increases with the age of the automobile. A sample of 26 automobiles 4 years old showed a sample standard deviation for annual repair costs of $171.3 and a sample of 23 automobiles 2 years old showed a sample standard deviation for annual repair costs of $118.38. Let 4 year old automobiles be represented by population 1. The data is located in the Microsoft Excel Online file below. Open spreadsheet State the null and alternative versions of the research hypothesis that the variance in annual repair costs is larger for the older automobiles. H 0 : ?2 1 _____ ?2 2 H a : ?2 1 ______?2 2 Conduct the hypothesis test at a 0.1 level of significance. Calculate the value of the test statistic (2 decimals). _____ Calculate the critical value (2 decimals). _____ Calculate the p-value (4 decimals). ____ Reject null hypothesis? What is your conclusion?
11.2
Most individuals are aware of the fact that the average annual repair cost for an automobile depends on the age of the automobile. A researcher is interested in finding out whether the variance of the annual repair costs also increases with the age of the automobile. A sample of 26 automobiles 4 years old showed a sample standard deviation for annual repair costs of $171.3 and a sample of 23 automobiles 2 years old showed a sample standard deviation for annual repair costs of $118.38. Let 4 year old automobiles be represented by population 1. The data is located in the Microsoft Excel Online file below.
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State the null and alternative versions of the research hypothesis that the variance in annual repair costs is larger for the older automobiles.
H 0 : ?2 1 _____ ?2 2
H a : ?2 1 ______?2 2
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Conduct the hypothesis test at a 0.1 level of significance.
Calculate the value of the test statistic (2 decimals).
_____
Calculate the critical value (2 decimals).
_____
Calculate the p-value (4 decimals).
____
Reject null hypothesis?
What is your conclusion?
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