a doctor wants to esimate the hdl cholesterol of all 2029 ye

a doctor wants to esimate the hdl cholesterol of all 20-29 year old females. how many subjects are needed to estimate the hdl cholestorol within 3 points with 99% confidence assuming S=17.1suppose the doctor would be content with 90% confidence. how does the decrease in confidence affect the samples size required?

a 99% confidence level rquires _______ subjects.
how does the decrease in confidence affect the sample size required

Solution

Given a=1-0.99 = 0.1, Z(0.005) = 2.58 (from standard normal table)

So n=(Z*s/E)^2

=(2.58*17.1/3)^2

=216.2664

Take n=217

-----------------------------------------------------------------------------------------------

When we decrease in confidence, the sample size decreases.