1. The problem statement, all variables and given/known data This is a problem that I really liked and that I want to share with you. Firstly because of the story around it, secondly because of the unexpected solution, and finally because it can be investigated with a computer for those who are the least comfortable with maths. Everybody is invited to participate, but don't forget this is for the 16 to 18 years old. problem: The chief of the forty thieves is finally captured and brought before the sultan, chained, and surrounded by 12 janissaries (https://en.wikipedia.org/wiki/Janissaries). The sultan tells him 'you can still save your life. Here are five black balls, and five white balls. Distribute them as you wish between these two boxes. I will then make them indistinguishable, and will shake them. You will then be blindfolded by one of my janissaries, and you will have to choose a box, and pick a ball. If the ball is white, I will spare you. If it is black ... ' and he shows him the shiny blade of his guard's scimitar (https://en.wikipedia.org/wiki/Scimitar). How should the chief of the forty thieves make his choice in order to maximize his chances of survival ?