Q. 2 B4.7( 3 Votes )

Assume that each child born is equally likely to be a boy or a girl. If a family has two children, what is the conditional probability that both are girls given that

at least one is a girl?

Answer :

At least one is a girl


Let C be the event that at least one is a girl


Then C = {(b, g), (g, b), (g, g)}, n(C) = 3


And the corresponding probability becomes



The sample space for the both girls is girl child and at least one is a girl will become


(AC) = {(g, g)}, n(AC)=1


And the corresponding probability becomes



So the conditional probability that both are girls given that the youngest is a girl is



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