In a test of the effectiveness of garlic for lowering cholesterol,

45

subjects were treated with garlic in a processed tablet form. Cholesterol levels were measured before and after the treatment. The changes

(beforeafter)

in their levels of LDL cholesterol (in mg/dL) have a mean of

3.4

and a standard deviation of

19.3.

Construct a

99%

confidence 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?