A small plastic ball of mass 6.10 10^-3 kg and charge +0.150 µC?

A small plastic ball of mass 6.10 10^-3 kg and charge +0.150 µC is suspended from an insulating thread and hangs between the plates of a capacitor. The ball is in equilibrium, with the thread making an angle of 30.0° with respect to the vertical. The area of each plate is 0.0150 m2. What is the magnitude of the charge on each plate?

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i tried 9.20*10^-22 but not the answer