Answer: 456
Explanation:
Given : Significance level : [tex]\alpha= 1-0.98=0.02[/tex]
Critical value : [tex]z_{\alpha/2}=2.33[/tex]
Margin of error : [tex]E=\pm0.05[/tex]
The prior proportion of employee e-mail is not business related: [tex]p=0.30[/tex]
The formula to find the sample size is given by :-
[tex]n=(p(1-p))(\dfrac{z_{\alpha/2}}{E})^2[/tex]
i.e. [tex]n=(0.3(0.7))(\dfrac{(2.33)}{0.05})^2=456.0276\approx456[/tex]
Hence, Elwin should sample 456 e-mail messages.
