So this is just a Voltage source capacitor circuit
[tex]V_{rms}=100 V, I_{rms}=2.60~ma, ~and~frequency~f=50Hz
\text{current in the circuit will be}=I_{rms}=\dfrac{V_{rms}}{X_{c}},X_{c}=\dfrac{1}{j \omega C}\\I_{rms}=V_{rms}*j \omega C=V_{rms}*(2 \pi f)C \angle 90=\left (2.60*10^{-3} \right )
[/tex]
Now just plug in the values and find out C
