what the question states :
"Events A and B are such that:
p(A) = 5/12
p(A|notB)=7/12
P(A intersection B ) =1/8 "
Would I be correct if I assume that Not B refers to A ? , so then i can draw a probability tree.
The question then asks for :
i) P(B)
ii) P(A|B)
iii) P(B|A)
iv) P(A U B)
P(B|A) is easy since P(A intersection B) / P(A) = 0.3
Had i known P(B) iv) would have been easy as well.
How can P(B) be found.. ?
Well I know this:
$\displaystyle \begin{align*}P(B) &= P(A\cap B) &+ P(notA\cap B)\end{align*}$
where
$\displaystyle \begin{align*}P(notA\cap B) &=P(A).P(B|notA)\end{align*}$