Question

n a test of the effectiveness of garlic for lowering​ cholesterol, 43 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 4.6 and a standard deviation of 16.3. 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 u​?

Answer 1

The 90 % confidence interval of , the population mean of the net change in LDL cholesterol after the garlic treatment is :

where ,

Degrees of freedom = 43-1=42

Now ,

Required confidence interval :

Since , the confidence interval doesnot contain the value 0 or any negative value , hence we can say that the new treatment with garlic has no effect in reducing the cholesterol level .

The confidence interval estimate of the population mean is