SOLUTION: 5. A watch manufacturer creates watch springs whose properties must be consistent. In particular, the standard deviation in their weights must be no greater than 3.0 grams. Fifte

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Question 339300: 5. A watch manufacturer creates watch springs whose properties must be consistent. In particular, the standard deviation in their weights must be no greater than 3.0 grams. Fifteen watch springs are selected from the production line and measured; their weights are 2, 4, 10, 10, 8, 8, 9, 10, 9, 5, 3, 2, 4, 2, and 2 grams. Assume = 0.01.
· State the null and alternate hypotheses
· Calculate the sample standard deviation
· Determine which test statistic is appropriate (chi-square or F), and calculate its value.
· Determine the critical value(s).
· State your decision: Should the null hypothesis be rejected?
(Points :10)

Answer by jrfrunner(365) About Me  (Show Source):
You can put this solution on YOUR website!
· State the null and alternate hypotheses
Ho: sigma=3
Ha: sigma%3C3
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· Calculate the sample standard deviation
s=3.335
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· Determine which test statistic is appropriate (chi-square or F), and calculate its value.
test statistic: %28n-1%29%2AS%5E2%2F%28sigma%5B0%5D%29%5E2=%2815-1%29%2A3.335%5E2%2F3%5E2=17.30
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· Determine the critical value(s).
lower tail
Chi^2 (1-alpha, dof)=chi^2(0.99,14)=4.66
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· State your decision: Should the null hypothesis be rejected?
since test statistic=17.30>critical value=4.66 cannot reject Ho.
Conclusion: No evidence against sigma=3