Do you know that ?
Events A & B are such that P(AB) = 1/3, P(B|A)= 1/4, and P(B'|A') = 4/5.
Hence find a) P(B'|A) b)P(AnB) c) P(B) d) P(AUB)
I really do not know where to start with this :S
I've been staring at it for 1/2 hour and still haven't got anywhere