Confidence Level Questions, statistics homework help

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Confidence Level Questions, statistics homework help

A doctor wants to estimate the mean HDL cholesterol of all​ 20- to​ 29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 33 points with 99% confidence assuming s = 17.6 based on earlier​ studies? Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample size​ required?

a) A​ 99% confidence level requires ____ subjects. ​

(Round up to the nearest​ subject.)

b) A​ 90% confidence level requires ____ subjects. ​

(Round up to the nearest​ subject.)

c)How does the decrease in confidence affect the sample size​ required?