Question

In a test of the 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 (before−​after) in their levels of LDL cholesterol​ (in mg/dL) have a mean of 4.9 and a standard deviation of 15.4. Construct a 99​% 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 a t distribution table.

What is the confidence interval estimate of the population mean μ​?

?? ​mg/dL < μ < ?? ​mg/dL

Answer 1

t critical value at 0.01 level at 41 df = 2.701

99% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

4.9 - 2.701 * 15.4 / sqrt(42) < < 4.9 + 2.701 * 15.4 / sqrt(42)

-1.5183 < < 11.3183