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

0.04 with 90​% confidence if

​(a) she uses a previous estimate of 0.36​?

​(b) she does not use any prior​ estimates?

Answer 1

Given that, margin of error ( E ) = 0.04

A 90% confidence level has significance level = 0.10 and critical value is,

a) She uses a pevious estimate of p = 0.36

We want to find, the sample size ( n ),

Therefore, required sample size is 390

b) she does not use any prior estimates, then assume p=0.5 and sample size is,

Therefore, required sample is 423