\[d_{1} = \ \ 6\ м;\ d_{2} = 10\ м:\]
\[\frac{C_{1}}{C_{2}} = \frac{2\pi R_{1}}{2\pi R_{2}} = \frac{\pi d_{1}}{\pi d_{2}} = \frac{d_{1}}{d_{2}} = \frac{6}{10} = \frac{3}{5}.\]
\[Ответ:\ \ 3\ :5.\]