In a large crowd,there are three times as many men as women.Three people are chosen at random.Assuming that there are so many people that choosing three has a negligible effect on the proportion of men to women,find the probability that they are (a) all men (b) 2 women and 1 man

Answer 1

pr(man)=1/4
pr(man,man,man)=(1/4)^3
Pr(2w,1m)..
can occur wwm,wmw,mww three ways
pr(2w,1m)=3*(3/4)^2(1/4)
which is the same as 3!/1!2! *(3/4)^2*(1/4)

Answer 2

the tree diagram