Question

1. Here are summary statistics for randomly selected weights of newborn girls: n=159, x=28.8 hg, s=7.7 hg.Construct a confidence interval estimate of the mean. Use a 98% confidence level. Are these results very different from the confidence interval 26.6 hg<u<32.0 hg with only 13 sample values, x=29m3 hg, and s= 3.6 hg?

What is the confidence interval for the population mean u?

__ hg<u<___ hg

2. A data set includes 109 body temperatures of healthy adult humans having a mean of 98.3 F and a standard deviation of 0.54 F. Construct a 99% confidence interval estimate of the mean body temperature of all healthy humans. What does the mean suggest about the use of 98.6 F as the mean body temperature?
What is the confidence interval estimate of the population mean u?

___F<u<____F

3.In a test of the effectiveness of garlic for lowering cholesterol, 48 subjects were treated with garlic in a processed tablet form. Cholesterol levels were measured before and after the treatment. The changes in ther levels of LDL cholesterol (in mg/dL) have a mean of 4.4 and a standard deviation of 15.9. 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?

__mg/dL<u<___mg/dL

Answer 1

1:

It is narrower than confidence interval with n=13.

2:

Since 98.6 does not lie in the above interval so we cannot take 98.6 F as the mean body temperature at 99% confidence level.

3:

Since confidence interval does not contain zero so there is evidence to conclude that garlic is effective.

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