In a test of the effectiveness of garlic for lowering choles

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 mg/dL) have a mean of 2.9 and a standard deviation of 18.8. Complete parts (a) and (b) below. What is the best point estimate of the population mean net change in LDL cholesterol after the garlic treatment? The best point estimate is mg/dL. Construct a 90% 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? What is the confidence interval estimate of the population mean mu? What does the confidence interval suggest about the effectiveness of the treatment?

Solution

a. 2.8 mg/dL

b. From the z-table, the 90% confidence level z-value = 1.645
Sample mean = 2.8
Standard deviation = 16.8
Standard error of mean = ? / ? n
Standard error of mean = 16.8 / ? 43
SE = 16.8/6.5574
Standard error of mean 2.562
90% confidence interval 2.8-(1.65)(2.562) and 2.8+(1.65)(2.562)

(-1.4273,7.0273 )

A.