Question

P(A∩B)=1150,P(A|B)=1120,P(B)=?

Answer 1

Conditional probability can be described using the following rule:
P ( A | B ) = P ( A ∩ B ) / P ( B )

Now for the givens we have:
P(A∩B)=1150 and 
P(A|B)=1120

Substituting with these givens in the above mentioned equations, we can get P(B) as follows:
1120 = 1150 / P(B)
P(B) = 1150 / 1120 = 1.02678