The problem is rather old, but very famous, that’s why I hope someone hasn’t come across it yet, and will get pleasure trying to solve it :o)
Let suppose that Klavdia Ivanovna (or what was her name) from a famous movie The Twelve Chairs hid her diamonds inside one of the chairs not for sure, but with 90% probability. What is the probability to find the diamonds in the 12 th chair after all the 11 chairs have been cut open and diamonds were not found inside one of them?
