A series LCR circuit driven by 300V at a frequency of 50 Hz contains a resistance $\mathrm{R}=3\mathrm{k\Omega }$, an inductor of inductive reactance ${\mathrm{X}}_{\mathrm{L}}=250\mathrm{\pi }\mathrm{\Omega }$  and an unknown capacitor. The value of capacitance to maximize the average power should be : $\left(\mathrm{Take}{\mathrm{\pi }}^2=10\right)$