311. Of two banks, one pays $p^{\%} \%$ annually, with interest compounded semi-annually; the second pays $q^{\%} \%$, with interest compounded monthly. What relationship must exist between $p$ and $q$ for placing capital in both banks to be equally profitable?
311. 

$$
\left(1+\frac{p}{2 \times 100}\right)^{2}=\left(1+\frac{q}{12 \times 100}\right)^{12}
$$