Question

In 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 4.8 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? Click here to view at distribution table. Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. What is the confidence interval estimate of the population mean u? mg/dL<< mg/dL (Round to two decimal places as needed.) What does the confidence interval suggest about the effectiveness of the treatment? O A. The confidence interval limits contain 0, suggesting that the garlic treatment did not affect the LDL cholesterol levels. O B. The confidence interval limits do not contain 0, suggesting that the garlic treatment did not affect the LDL cholesterol levels. O C. The confidence interval limits contain 0, suggesting that the garlic treatment did affect the LDL cholesterol levels. OD. The confidence interval limits do not contain 0, suggesting that the garlic treatment did affect the LDL cholesterol levels.

Answer 1

Solution:

Confidence interval for Population mean is given as below:

Confidence interval = Xbar ± t*S/sqrt(n)

We are given

Xbar = 4.8

S = 16.6

n = 43

df = n – 1 = 42

Confidence level = 95%

Critical t value = 2.0181

(by using t-table or excel)

Confidence interval = Xbar ± t*S/sqrt(n)

Confidence interval = 4.8 ± 2.0181*16.6/sqrt(43)

Confidence interval = 4.8 ± 2.0181*2.531476268

Confidence interval = 4.8 ± 5.1087

Lower limit = 4.8 - 5.1087 = -0.31

Upper limit = 4.8 + 5.1087 = 9.91

-0.31 mg/dL < µ < 9.91 mg/dL

What does the confidence interval suggest about the effectiveness of the treatment?

A. The confidence interval limits contain 0, suggesting that the garlic treatment did not affect the LDL cholesterol levels.