Unformatted text preview: 10.22 The hardness of a certain rubber (in degrees Shore) is claimed to be 65. Fourteen specimens are tested, resulting in an average hardness measure of 63.1 and a standard deviation of 1.4. Is there suﬃcient evidence to reject the claim, at the 5% level of signiﬁcance? What assumption is necessary for your answer to be valid? 10.36 Aptitude tests should produce scores with a large amount of variation so that an administrator can distinguish between persons with low aptitude and persons with high aptitude. The standard test used by a certain industry has been producing scores with a standard deviation of 5 points. A new test is tried on 20 prospective employees and produces a sample standard deviation of 8 points. Are scores from the new test signiﬁcantly more variable than scores from the standard? Use α = 0 . 05 ....
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 Fall '08
 Kyung
 Statistics, Standard Deviation

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