A standard American deck of cards contains 52 cards in four “suits”:
♣ clubs ♦ diamonds ♥ hearts ♠ spades
Each card also has a “rank”. There are 13 ranks: 2, 3, 4, 5, 6, 7, 8, 9, 10, J (jack), Q (queen), K (king), A (ace). Every suit-rank combination occurs in the deck, so a typical card might be called “the 7 of clubs” or “the queen of hearts”.
Suppose we shuffle a deck (meaning that we put the cards in random order), then we draw a card off the top.
What is the probability that this card has an even number on it? (Jacks, queens, kings, and aces do not have numbers on them.)
There are 40 cards with numbers
20 are even numbers out of 52 cards
20/52 = 5/13