Possible Duplicate:
A probability problem
Let $A$ and $B$ be events, $P(A) = \frac{1}{4} $, $P(A\cup B) = \frac{1}{3} $ and $ P (B) = p $.
- Find $p$, if $A$ and $B$ are mutually exclusive.
- Find $p$, if $A$ and $B$ are independent.
- Find $p$, if $A$ is a subset $B$.
I know for 1) mutually exclusive: $P(A) + P(B) = P(A \cup B)$, but how I can find p ? I don't know how to solve it. Please help me.
Obs: Sorry for duplicate post.