In an $LCR$ series circuit, an inductor $30 \mathrm{mH}$ and a resistor $1 \mathrm{\Omega }$ are connected to an $\mathrm{AC}$ source of angular frequency $300 \mathrm{rad} {\mathrm{s}}^{-1}.$ The value of capacitance for which the current leads the voltage by $45°$ is $\frac{1}{x}\times {10}^{-3} \mathrm{F}$. Then the value of $x$ is