Question

Someone draws a card at random from a deck, and then, without replacing the first card, draws a second card. What is the probability that both cards will be aces?

Answer 1

Event A is that the first card is an ace. Since 4 of the 52 cards are aces, P(A) = 4/52 = 1/13. Given that the first card is an ace, what is the probability that the second card will be an ace as well? Of the 51 remaining cards, 3 are aces. Therefore, P(B|A) = 3/51 = 1/17, and the probability of A and B is 1/13 × 1/17 = 1/221. The same reasoning is applied to marbles in a jar