Question

A political candidate has asked you to conduct a poll to determine what percentage of people support her. If the candidate only wants a 4% margin of error at a 95% confidence level, what size of sample is needed? Hint: Textbook Video [+]

Answer 1

Answer:-

Given that:-

p=1-=0.5

margin of error = E = 4% = 0.04

At 95% confidence level the Z is,

$\alpha =1-95\%$

$\alpha =1-0.95=0.05$

$\alpha/2 =0.025$

$Z_{\alpha/2} =Z_{0.025}=1.960$

sample size $= n = (Z_{\alpha/2}/E)^{2}*\widehat{p}*(1-\widehat{p})$

=600.25

Sample size = n = 600