A doctor wants to estimate the HDL cholesterol of all 20 to

A doctor wants to estimate the HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the HDL cholesterol within

points with

99 %99%

confidence assuming

sigma equals 13.6 question mark =13.6?

Suppose the doctor would be content with

95 %95%

confidence. How does the decrease in confidence affect the sample size required