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 4 points with 99 % confidence assuming s equals 12.2 based on earlier​ studies? Suppose the doctor would be content with 90 % confidence. How does the decrease in confidence affect the sample size​ required?
LOADING... Click the icon to view a partial table of critical values.
A​ 99% confidence level requires
nothing subjects. ​(Round up to the nearest​ subject.)