Question
A bag contains 3 blue, 2 green, and 5 black pens. If
five pens are selected randomly, what is the probability that exactly two are green and three are black?Solution
Total number of outcomes = C (n, r) = C (10,5) 
= 252 number of favorable outcomes = C (5,3) × C (2,2) = 10 × 1 = 10 ∴ Required probability = 10/252 = 5/126
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