You are dealt cards from a standard deck of 52 cards. How many ways can you be dealt 5 cards so that the 5 cards contain two cards of one rank, two cards of another rank, and a fifth card of a third rank? We say that such a hand has two pairs. For example, the hand QQ225 has two pairs. (Assume that the order of the cards does not matter.)
First, I am 99.99% sure this is from AoPS Intro to Counting and Probabilty, but at this point, I'm too tired to care.
For card one you hav 52/52 chance, for the second, you have 4-1 =3 3/51 chance
I'll let you continue from here
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