Poker is a card game, where a poker-hand is made up of 5 cards from a deck of 52 cards. A deck of 52 cards has four suits: spades, hearts, diamond clubs and 13 denominations. Assume the equally likely model for dealing poker-hands.
a) How many poker-hands are possible?
b) A poker-hand called "three of a kind" has 3 cards of one denomination and 2 other cards neither of which is of that denomination. What is its probability?