Originally posted by PBE6
Here's some more food for thought. This is the solution provided on "Shack's Math Problems" where this problem was taken from. Note that the solution is "doesn't matter" as evereyone has been saying, and as I originally thought (according to my first post). However, note the 2nd last paragraph:
Question:
http://mathproblems.info//group1.html
So ...[text shortened]... e is an exhaustive analysis of this paradox: www.u.arizona.edu/~chalmers/papers/envelope.html.
As the exhaustive analysis correctly points out, it is possible for problems to arise. However, this won't happen if the distribution X of the total money is 'nice', ie with finite mean and variance, which it would be unless the person offering you the envelopes was someone of infinite means.
In your original description of the problem, you said that you get the chance to switch
before you open the envelope. This is key, as it means that the distribution of X is irrelevant when you make your decision, as there's nothing to distinguish between the envelopes. On the other hand, if you pick up one envelope and look inside before deciding whether to switch, then you can start speculating on the distribution of X, and the problem becomes more complicated.