4 ms·
I think the problem is they effectively change a problem from having 2 possibilities (either you get $X or you get 2 * $X) to a problem that has 3 possibilities
by jwegan 16y ago
I think the problem is they effectively change a problem from having 2 possibilities (either you get $X or you get 2 * $X) to a problem that has 3 possibilities: A/2 (1 possible amount in the other envelope), A (the amount in your envelope), and 2A (the other possible amount in the other envelope) by fixing A relative to the hypothetical amount you could have in your envelope.
- Uhhrrr 16y agoYeah - it's not really (0.5A + 2A)/2, it's (0.5A1 + 2A2)/2, where A1=2*X (as you have above) and A2=X. Substituting, your expected value upon changing is 3X/2, which is, surprise surprise, the same as the expected value for the envelope you already have.