You are playing a game where there are 9 boxes laid out in a row, numbered 1 through 9 from left to right. Randomly placed in one of the boxes is a slip of paper that says "GAME OVER". The other eight boxes each contain $1000.
You are to pick the boxes one at a time. If you pick a box with $1000, you keep the money and you must pick another box. If at any point you select the box that says "GAME OVER", the game ends and you leave with the prize money you've accumulated to that point. The only catch is, the host of the game show will tell you which direction the "GAME OVER" box is in, and you must guess your next box in that direction (it's like a guessing game where you have to guess a number from 1 to 9, and after each guess the host tells you "higher" or "lower" until you finally guess the number he is thinking of). However, the goal of this game is not to land on the "GAME OVER" box (since you eventually will), but to maximize the number of guesses you take (and thus your profit) before you land on it.
Question 1: Is there an optimal strategy for this game? If so, what is it and what is your expected profit? If not, why not?
Question 2: What if you were the host, and instead of randomly placing the "GAME OVER" box, you could choose where it went - is there a strategy that would minimize the expected profit of the contestant?
(In reply to re: Observation re Question 2
by Cory Taylor)
I respectfully disagree. the $4,888,89 strategy is valid. It always
chooses a box in the same direction as
the host last indicated the "game over" box to be in.
Start at 5.
If the host says "Higher", move to 9 (which is higher).
If the game is not over, then the host says "Lower".
Move to 1, which is both lower and guaranteed to be safe. The host will say "Higher".
Then move to 2, which is higher. The host will again say "Higher".
Then move to 3, which is higher. The host will again say "Higher".
Then move to 4, which is higher. The host will again say "Higher".
Then move to 6, which is higher. If the game is not over, the host will again say "Higher".
Then move to 7, which is higher. If the game is not over, the host will again say "Higher".
Then move to 8, at which point the game is over.
Expected winnings = $4,888.89