Re: probability question
The question is ambiguous. MickeyHoldem pointed to an explanation if there is an infinite population of people. In that case the answer is 3*0.4*0.6^2 = 42.3%. You answered it assuming the population is 10 people in which case the answer is 50%.
If the population size is N, the answer is:
C(0.4*N,1)*C(0.6*N,2)/C(N,3)
= 0.4*N*[0.6*N*(0.6*N-1)/2]/[N*(N-1)*(N-2)/6]
=0.72*N*(0.6*N-1)/[(N-1)*(N-2)]
This goes from a high of 0.6 (N = 5) down to 0.432 as N increases.
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