It's Not As Simple As You Think It Is
There is an equally likely chance of having a boy or girl as a child when having one child. The Johnsons have two children, one of which is a boy. The probability that the other is a girl can be represented by the expression where and are Coprime integers. Evaluate .
The answer is 5.
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1 solution
When there are two children, there are four possibilities.
BB GG BG GB
It was definitely not GG since we know that there was one boy. There are two possibilities (BG and GB) that contain one girl out of three remaining possiblities
Thus the probability is 2/3. 2 + 3 = 5