If A and B are two events of the same sample, S, then:
The conditional probability of event A on B, P (A|B), is the probability of event A when the event of B has already occurred.
Calculate the probability of a 6 being rolled by a die if it is already known that the result is even.
Two events A and B are independent if:
p(A|B) = p(A)
Two events A and B are dependent if:
p(A|B) ≠ p(A)