2) If in a city there is a mathematician for every 320 inhabitants, what is the percentage of mathematicians?
(A) $3.2 \%$
(B) $0.32 \%$
(C) $3.125 \%$
(D) $0.3125 \%$
(E) none of the above.

![](https://cdn.mathpix.com/cropped/2024_04_17_58bef2a2a14f9f84b61bg-1.jpg?height=290&width=414&top_left_y=1455&top_left_x=983)
2) The answer is $\mathbf{( D )}$.

Indeed, we have $\frac{1}{320}=0.003125=0.3125\%$.