Algebra 2 (1st Edition)

$n=15625$.
If the margin of error is $\pm0.8\%$, then our equation is: $\pm\frac{1}{\sqrt n}\cdot 100\%=\pm0.8\%=\pm0.008\\\frac{1}{\sqrt n}=0.008\\125=\sqrt{n}\\n=15625$.