:::That is not fair.  I am very interested in making this page available to the widest variety of readers but I cannot so what you are suggesting that will achieve this.  The question (the Whitaker/vo Savant version) is badly stated and open to misinterpretation but the evidence we have is that nearly everybody does interpret the problem in the same (standard) way.  Misinterpretation of the question is not the main reason that people get the answer wrong. There is ample evidence that even when the question is carefully and rigorously expalined to people they still get it wrong. Any help in helping people to understand why the answer is 2/3 is most welcome.