Question

A researcher wishes to estimate the proportion of adults who have​ high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within 0.01 with 95​% confidence if ​(a) she uses a previous estimate of 0.34​? ​(b) she does not use any prior​ estimates?

Answer 1

Solution :

Given that,

(a)

= 0.34

1 - = 1 - 0.34 = 0.66

margin of error = E = 0.01

Z/2 = 1.96

sample size = n = (Z / 2 / E )2 * * (1 - )

= (1.96 / 0.01)2 * 0.34 * 0.66

= 8621

sample size = 8621

(b)

= 1 - = 0.5

margin of error = E = 0.01

Z/2 = 1.96

sample size = n = (Z / 2 / E )2 * * (1 - )

= (1.96 / 0.01)2 * 0.5 - 0.5

= 9604

sample size = 9604