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 in their levels of LDL cholesterol )in mf/dl) have a mean of 5.6 and standard deviation of 19.5

a. What is the best point estimate of the population mean net change in LDL cholesterol after the garlic treatment?

b. Construct a 90% confidence interval of the mean net change in LDL cholesterol after the garlic treatment.

c. What does the confidence interval suggest about the effectiveness of garlic in reducing LDL cholesterol.