Girl-Boy
A Couple decided to have offspring every 2 years until they have at least a boy and a girl. If every time only 1 infant(Girl/Boy) is born. What is the expected number of children they will have?
Note : at any instant before birth, Both Girl and boy are equiprobable.
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1 solution
For the first time, it can be either a girl or a boy. It does not matter. You can consider it as the expected number of flips required to get Head/Tail.
Case 1 : If it is a Girl: then expected number of turns for a boy will be 2. so total 3 Children.
Case 2 : If it is a boy: then expected number of turns for a girl will be 2. so total 3 Children.
Either Case there will be 3 Children.