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 4 points with 99% confidence assuming sigma =13.3? Suppose the doctor would be content with 95% 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 95% confidence level requires [ ] subjects (Round up to the nearest whole number as needed. ) How does the decrease in confidence affect the sample size required? A The lower the confidence level the smaller the sample size B The sample size is the same for all levels of confidence. C The lower the confidence level the target 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