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 0.03 with 99?% confidence if ?(a) she uses a previous estimate of 0.48?? ?(b) she does not use any prior? estimates?

Answer 1

Solution :

Given that,

margin of error = E = 0.03

Z_/2 = 2.576

(a)

= 0.48

1 - = 0.52

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

= (2.576 / 0.03)² * 0.48 * 0.52

= 1841

sample size = n = 1841

(b)

= 0.5

1 - = 0.5

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

= (2.576 / 0.03)² * 0.5 * 0.5

= 1844

sample size = n = 1844