Please read Re^7: Marilyn Vos Savant's Monty Hall problem carefully. You'll find that it is not enough to say how much knowledge Mr. Hall has - to make the answer unambiguous you also need to specify how Mr. Hall will use that knowledge.

On the spooky math problem, there is no divide by an infinite number problem, but there is a lot of subtle behaviour with infinity lurking around. I strongly recommend against coming to any opinion without thinking it through very carefully. It took me about a week to really understand what was happening when I first ran into the problem. (It didn't help that Laurie let me get myself well and truly convinced that there was no way that you could beat 50% before he gave me the answer and told me to figure out for myself why it worked...)

Given any pair of numbers in the envelopes, and given the distribution from which you pick a random number, your probability of winning is well-defined and will be bigger than 50%. Depending on those three factors, the actual odds can be anywhere between (but not including) 50% and 100%. But you are not provided with sufficient information to figure out what the odds are.

In reply to Re^5: Marilyn Vos Savant's Monty Hall problem by tilly
in thread Marilyn Vos Savant's Monty Hall problem by mutated

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