Prochroma,
The mathematics is correct. The key is to realize that the second round (after Monty opened Door Two) probability for each of the remaining two doors should not be treated equally. This is what makes it such a counter intuitive problem. The typical response is that there is a mistake and insist that the doors have equal weight. For a more detailed explanation please refer to http://mathforum.org/dr/math/faq/faq.monty.hall.html.
Cheers,
Jeff
Wed, 01 Sep 2010 12:36:47 +0200