Prob( getting for 1's in first 4 throws) = (1/6)^2 * 5/6 = 5/ 7776
There are 5 ways to get 4 1's so this Probability is 25/7776
so probability of getting 2 - 6 4 times = 5 * 25 / 7776
= 125 / 7776 = Prob ( 4 of a kind)
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