Question 177279
A U.S. dime is supposed to weigh 2.268 grams. A random sample of 15 circulated dimes showed a mean weight of 2.256 grams with a standard deviation of .026 grams. 
9.55 A U.S. dime is supposed to weigh 2.268 grams. A random sample of 15 circulated dimes showed a mean weight of 2.256 grams with a standard deviation of .026 grams.
(a) Using α = .05, is the mean weight of all circulated dimes lower than the specification? State your hypotheses and decision rule.
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Ho: u = 2.268
Ha: u < 2.268
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If the test statistic is less than -1.645, reject Ho.
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(b) Why might circulated dimes weigh less than the mint specification? 
Because of wear and tear on the coins.
Cheers,
Stan H.