A radioactive sample has an average life of 30 ms and is decaying. A capacitor of capacitance 200 μ F is first charged and later connected with…

A radioactive sample has an average life of $\displaystyle 30$ ms and is decaying. A capacitor of capacitance $\displaystyle 200 \mu \mathrm{~F}$ is first charged and later connected with resistor $\displaystyle { }^{\prime} \mathrm{R}^{\prime}$. If the ratio of charge on capacitor to the activity of radioactive sample is fixed with respect to time then the value of ' R ' should be \_\_\_\_ $\displaystyle \Omega$