Question 386078
A special diet should reduce cholesterol below 200. An SRS of 50 patients at risk had an average cholesterol of -x(mean)=192, with standard deviation s=21. Is this sufficient evidence that the diet is effective? Assume the distribution of the cholesterol for patients is approximately normal with mean u. 
1)What is an appropriate hypothesis?
Ho: u>= 200, 
Ha: u< 200 (this is the claim; might as well make it a hypotheses)
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2)The appropriate degrees of freedom for this test are:
df = 49 because n = 50
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3)Based on the data, one sample t-statistic is?
t(192) = (192-200)/[21/sqrt(50) = -2.6937
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Cheers,
Stan H.