There are 6 couples (12 people). 4 people are selected at random. What is the probability that exactly one couple will be selected ?

One Answer on this Question

1. Prob(choosing two people who are a couple from 6 couples) = 1/6
   We have 5 couple left (10 people)
   Prob(choosing a person A from 10 people) = 1/10
   Prob(choosing 1 person who is not a couple of A) = 1/8

   Prob(choosing 4 people that has exactly one couple) = 1/6*1/8*1/10 = 0.0021

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