A doctor wants to estimate the HDL cholesterol of all20- to29-year-old females. How many subjects are needed to estimate the HDL cholesterol within 4 points with 99% confidence assuming =18.5? Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample sizerequired?

A99% confidence level requires

nothing

subjects.

(Round up to the nearest whole number asneeded.)