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 33 points with 99%confidence assuming s=13.2 based on earlier​ studies? 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 subject)

A 95% confidence level requires _____subjects? (Round up to the nearest subject)

Answer 1

Given that Margin of Errot = 33; S=13.2 12.0.0r, Z-2.5758. n=122 2 17 (203) (5788x132) = 1.0615 XS = 2.57 58 x 13.21 -- 13.212 =1.06155 33 n = 1.06155 At 95% conbidence interval 4+0.05, 220.025.4.96 n=/1.966103212 -) = 0.6146 33 m2 0.614-6) Sample size degreses in confidence decrease - with Interval demonstrate Error =3, to Margin of het us take n value . IME=3. J at 99% confidence interval n= ( x 27. 13.2 / 2-5758 - 128.44 125 [ n=125] = 14:37 ~ 75: At 95% CI natx)2 = (1.96x 13-2) =

as confidence interval decrease sample size also decrease