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 arc needed to estimate the HDL cholesterol within 3 points with 99% confidence assuming o - 11.8? Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample size required? A 99% confidence level requires subjects. (Round up to the nearest whole number as needed ) A 90% confidence level requires subjects. (Round up to the nearest whole number as needed.) How does the decrease in confidence affect the sample size required? The lower the confidence level the larger the sample size. The sample size is the same for all levels of confidence. The lower the confidence level the smaller the sample size.

Solution

samle size=(z*sigma/E)^2

when confidence level is 99%

sample required=(2.58*19.9/3)^2=293

when confidence level 95%

sample required=(1.96*19.9/3)^2=169

lowe the confidence level smaller the sample size