Question 1015146: In a test of the effectiveness of garlic for lowering cholesterol, 49 subjects were treated with raw garlic. Cholesterol level were measured before and after the treatment. The changes in their levels of LDL cholesterol (in mg/dL) had a mean of 0.4 and a standard deviation of 21.0. Construct a 95% confidence level interval estimate of the mean net change in LDL cholesterol after the garlic treatment. What does the confidence interval suggest about the effectiveness of garlic in reducing LDL cholesterol?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! Assuming a normally distributed population where the sample sd is an adequate estimate of the population sd,
t df=48 is the test statistic.
95% CI is +/-2.01*s/sqrt (49), where s is sd
=+/-2.01*21/7
=+/-6.03
add to mean
(-5.63, 6.43) units are mg/dL.
The interval contains 0, so that 0 is a reasonable value to assume, and we cannot conclude that garlic has any difference upon the LDL cholesterol levels.
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