A doctor wants to estimate the mean HDL cholesterol of all20- to29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 3

3 points with 99 %

99% confidence assuming s equals 15.3

s=15.3 based on earlierstudies? Suppose the doctor would be content with 95 %

95% confidence. How does the decrease in confidence affect the sample sizerequired?

A99% confidence level requires

nothing

subjects.