Question 187146
9.54 Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 75 randomly chosen fax transmissions during the next year, yielding a sample mean of 11.44 with a standard deviation of 2.15 pages. At the .05 level of significance, is the true mean greater than 10? Explain your decision.
Clearly state your decision on the null hypothesis.
Ho: u <= 10
Ha: u > 10
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test statistics: t(11.44) = (11.44-10)/[2.15/sqrt(75)] = 5.80
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p-value = P(t > 5.80) = 0.0000000766
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Since the p-value is less than 5%, reject Ho.
The true mean is greater than 10.
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Cheers,
Stan H.