4 ms·

Env A has $20 (we have it and know). Env B has $10 or $40 (equal chance). We swap. Now we hold Env B, which has $10 or $40 in it. We know the other envelope

by colomon 13y ago

Env A has $20 (we have it and know). Env B has $10 or $40 (equal chance). We swap. Now we hold Env B, which has $10 or $40 in it. We know the other envelope (Env A) is $20. Why would we switch again?

andrewflnr 13y ago
The original statement of the problem says you're offered the choice before you open the envelope. I guess I was sloppy about the $20 assumption too. As for the case you do know, I still feel wrong about the conclusion that you should switch, but I can't formalize it.