Given a dependency between two events, A and B, in order to determine P(A|B) you must know both P(A) and P(B). True or False?

Answer 1

I am not the best at this but I am decent so I would say true but I am not sure

Answer 2

Well P(A | B) = P( A ∩ B)/P(B)

So we definitely need P(B), but to know P( A ∩ B) does not mean
that we actually have to know P(A).