I think the question for this problem, is to find the capacitance. The working equation would be:
C = Q/V,
where
Q = It
Since f = 1/t, t = (1/300 kHz)(1 kHz/1,000 Hz) = 3.33×10⁻⁶ s
So,
Q = (310×10⁻⁶ A)(3.33×10⁻⁶ s)
Q = 1.033×10⁻⁹ C
Thus,
C = (1.033×10⁻⁹ C)/(3 V)
C = 3.44×10⁻¹⁰ F
