Locked in a dungeon, you are faced with five doors. One of them leads to freedom. The other four will lead you back to the starting room disoriented and confused, so that you will not remember which of the doors you have already tried and have to start again.

How many attempts do you expect to make on the average (statistically) before making it out?

(In reply to re: re: Simpler Solution by Nick Reed)

Linguini-

It is basically the same as your formula simplified to the case where all attempts have exactly the same chance of success. Your approach would be necessay if there were any way to occassionally eliminate one of the doors (say you can only go through a given door ten times before it locks), but as long as conditions NEVER change, then this is a simpler version.

Posted by TomM on 2002-06-06 16:44:16