`W=1/2CV^2`;`Q = CV`;`V = Q/C`
`W=1/2C (Q/C)^2 = 1/2Q^2/C`
`C = Q^2/(2W)`
` = (3000μ)^2/(2*150m)`
` = (9μ)/(300m)`
` = (9000μ)/(300)`
30μF