A researcher wishes to estimate the proportion of adults who

A researcher wishes to estimate the proportion of adults who have high speed internet. List the size sample that needs to be obtained if the researcher wants to estimate to be within 0.02 with 90% confidence.

Round up to the nearest interger please.

A. A previous estimate of 0.42 is uesed.

B. no prior estimates are used.

Solution

Given a=1-0.9=0.1, Z(0.05) = 1.645 (from standard normal table)

---------------------------------------------------------------------------------------------------------------

(A) n=(Z/E)^2*p*(1-p)

=(1.645/0.02)^2*0.42*(1-0.42)

=1647.969

Take n=1648

---------------------------------------------------------------------------------------------------------------

(B)n=(Z/E)^2*p*(1-p)

=(1.645/0.02)^2*0.5*(1-0.5)

=1691.266

Take n=1692