Question

If P(A) = 0.7, P(B) = 0.1, and P(A`nn`B)=0, what is P(B|A)? What about P(A|B)?

Answer 1

Both conditional probabilities are `0`.

Explanation:

Conditional probability is calculated as:

`P(A//B)=(P(AnnB))/(P(A))` If `P(AnnB)=0` then `P(A//B)` is also zero.

`P(B//A)` can be calculated in the same way (the numerator is also zero).

It can also be explained this way:

If events `A` and `B` cannot occur at the same time (`P(AnnB)=0`) then it is also impossible that `A` happened under condition of `B` or `B` under condition of `A`