One of each court card

Four cards are drawn at once from a deck of 52, so the hand is an unordered set. Find the probability that the hand consists of one king, one queen, one jack and one ace.

The sample space has \binom{52}{4} equally likely hands. The favourable hands choose one card from each of the four ranks, so there are 4^4 of them. The probability is 4^4/\binom{52}{4}.