In a test of effectiveness of garlic for lowering cholesterol 42 subjects were treated with garlic in a processed tablet form. cholesterol levels were measured before and after the treatment the changes and after the treatment the changes in their lives of LDL cholesterol (in mg/DL) have a mean of 5.4 and a standard deviation of 18.6
a) What is the best point estimate of the population mean net change in LDL cholesterol after the garlic treatment.
b) Construct a 95% confidence interval 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.