Question

Find the sample size needed to estimate the percentage of democrats among registered voters in Florida. Use a 0.01 margin of error, and use a confidence level of 96% and assume p=0.55

Answer 1

given data are:-

p = 0.55

margin of error (E) = 0.01

z critical value for 96% confidence level, both tailed test be:-

$z^*=2.054$[ in any blank cell of excel type =NORMSINV(0.98)]

the needed sample size be:-

$=\left ( \frac{z^*}{E} \right )^2*p*(1-p)$

$=\left ( \frac{2.054}{0.01} \right )^2*0.55*(1-0.55)$

$\approx\mathbf{10442}$

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