Solubility in water help

I need to determine the solubility product expression for both as well as the solubility in water. How do I do this?? Thanks for the help!

A. BaCrO4; Ksp = 2.1 ×10^-10
B. Ag2S; Ksp = 8 ×10^-5

1) BaCrO4 ----> Ba(2+) + CrO4(2-)
.........................s...........s

[Ba(2+)] * [CrO4(2-)] = s^2 = Kps -------> s = rad( Kps ) = 1,5 * 10^-5M

2) Ag2S ----> 2Ag(+1) + S(2-)
......................2s..........s

[Ag+]^2 * [S(2-)] = 4s^2 * s = 4s^3 = Kps -------> s = radCub( Kps / 4 ) = 2,714 * 10^-2M

Bye Bye :)