In a test of the effectiveness of garlic for lowering cholesterol, 49 subjects were treated with garlic in a processed tablet form.
Cholesterol levels were measured before and after the treatment. The changes (before-after) in their levels of LDL cholesterol (in
mg/dL) have a mean of 4.2 and a standard deviation of 16.6. Construct a 95% 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?