Answer
$n\approx1111$
Work Step by Step
If the margin of error is $\pm3\%$, then our equation is: $\pm\frac{1}{\sqrt n}\cdot 100\%=\pm3\%=\pm0.03\\\frac{1}{\sqrt n}=0.03\\33.333=\sqrt{n}\\n\approx1111$.
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