Question

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 2 points with 99 % confidence assuming s equals 11.6 based on earlier​ studies? Suppose the doctor would be content with 90 % confidence. How does the decrease in confidence affect the sample size​ required?

Answer 1

The number of needed subjects to estimate the mean HDL= 31

Step-by-step explanation:

Given that:

. standard deviation, s= 11.6

. Margin of error, ME = 2

s= 11.6

ME = 2

. The 90% margin of error is defined as:

ME = Z₀,₉÷₂ X σ÷√η

coeficient = (0,90/2)

2= 1.645 x 11.6/√η

√η= (1.645 x 11.6)÷ 2

η= √9.541

η= 30.888

η≈31