# Not what you think

**Discrete Mathematics**Level 5

Mr Mister has 2 children. One of these children is a boy who was born on a Tuesday. What is the probability that the other child is a boy?

If this probability can be written as \(\dfrac {a}{b}\), where \(a\) and \(b\) are coprime positive integers, find \(a+b\).

Assume that the probability of having a boy is half (if it is not a boy, it is a girl) and the probability of being born on Tuesday is \( \dfrac{1}{7} \) irrespective of gender.

Knowing which day one of the children was born is important.