$\left. \begin{matrix} KOH:M=0/01\Rightarrow \left[ O{{H}^{-}} \right]=0/01\Rightarrow \left[ {{H}^{+}} \right] ={{10}^{-12}}\Rightarrow pH=12  \\ HN{{O}_{3}}:M=0/001\Rightarrow \left[ {{H}^{+}} \right]=0/001\Rightarrow pH=3  \\ \end{matrix} \right\}\Rightarrow \frac{12}{3}=4$