The Probability of Two Events Both Occurring
If P(A) is the probability that A will occur, and P(B) is the probability the B will occur, the probability P(A, B) that both A and B will occur is:
Let's say one wants to determine the probability of receiving a Blackjack but only if the first card is a Ten valued card (i.e. a Ten, Jack, Queen or King). We know that there are 16 Ten valued cards in a 52 card deck. We also know there are four Aces in the deck. Therefore we know that P(A) = 16/52 and P(B) is 4/51. Therefore, we can say that the probability P(A,B) of selecting an Ace after a Ten has been dealt is P(A,B) =P(A)*P(B) = 16/52 * 4/51 = 0.3076923076923 * 0.07843137254902 = 0.02413273001508