I whipped together something here, before I saw that someone else did it too: http://ideone.com/jyPOhs http://ideone.com/jyPOhs It is the most counter-intuitiv

I whipped together something here, before I saw that someone else did it too: http://ideone.com/jyPOhs http://ideone.com/jyPOhs It is the most counter-intuitive statistic problem I know (worse than Monty Hall), it trips everyone up at first. No problem about the stubborness ;)