““Participants in a well-known experiment are given a choice of drawing a marble from one of two urns, in which red marbles win a prize: Urn A contains 10 marbles, of which 1 is red. Urn B contains 100 marbles, of which 8 are red. Which urn would you choose? The chances of winning are 10% in urn A and 8% in urn B, so making the right choice should be easy, but it is not: about 30%–40% of students choose the urn with the larger number of winning marbles, rather than the urn that provides a better chance of winning.””
