Discovering Statistics

A den for Learning

  • My Favourite Problems

    Polya’s Urn At time 0, an urn contains 1 black and 1 white ball. At each time 1,2,3,…, a ball is chosen at random from the urn and is replaced together with a new ball of the same colour. Just after time n, there are therefore n+2 balls in the urn, of which Bn+1 are…