Counting & ProbabilityHardCounting & Probability
Counting & Probability · Hard problem
How many -card hands from a standard -card deck contain exactly two pairs (two cards of one rank, two cards of a second rank, and one card of a third rank)?
How many -card hands from a standard -card deck contain exactly two pairs (two cards of one rank, two cards of a second rank, and one card of a third rank)?