Lycée Arago (Perpignan)
If some day you are bored try this experience: take a needle and drop it onto the floor. If the needle lands on a line between two strips you win, if not you lose (of course we consider a floor made of parallel strips of wood of the same width, and a needle shorter than the width of each floorboard). Repeat this experience until you are tired and, eventually calculate your success rate. Which value can we expect for that rate if we realize the experiment a large amount of times? Why may the result be interesting?