Question of the week – 15 November 2017

There was a record turnout at the Quiz this week: 26 teams!    One particular question caused a lot of discussion:

A person has two children, at least one of which is a girl; what is the probability that both are girls? 

Quelqu’un a deux enfants dont au moins une fille; quelle est la probabilité que les deux soient des filles?

What do you think?