Question 445128
Science fiction novels average 240 pages in length. The average length of 14 randomly chosen novels written by I. M. Wordy was 280 pages in length with a standard deviation of 40.
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Are Wordy's novels significantly longer than the average? 
Assume = .05. What is the test value, the critical value(s), and the conclusion?
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Ho: u <= 240
Ha: u > 240 (the question)
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Critical Value = invT(0.95 with df = 13) = 1.7709
sample mean = 280 
test stat: t(280) = (280-240)/[40/sqrt(14)] = 3.7417..
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Since the test stat is in the reject interval, reject Ho.
The test result supports a positive answer to the question.
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Cheers,
Stan H.