This game of chance for one person is loosely based on one round of the TV game show The Weakest Link. For comparison, each unit is, again loosely, based on $1000 on the show. This game of chance is done for only one round and only one person is playing.

The rules of the game of chance:

You roll a die 27 times, or until you win a 128-unit prize. Each roll is scored as a Loss if the die comes up 1 or 2; a Win otherwise.

The game starts off at stage 0. A Win advances to the next stage; a Loss reverts the stage to 0.

Before any roll, at your discretion you may say "Bank", which results in your winnings being increased by an amount equal to 2^(s-1) where s is the stage number, except nothing in stage 0: 1 unit if in stage 1, through 128 units in stage 8, but when you Bank, the stage reverts to 0 again.

If you get a Win in stage 8, not only is 128 added to any previous winnings, but the game ends even if 27 rolls have not yet taken place. Getting a stage-8 Win and banking are the only two ways of adding to your winnings.

If you get a Win on the 27th (last) roll you keep the value for that stage (an automatic bank after your successful roll).

Is it ever advantageous to Bank?

What's the expected value of the game, given optimal strategy?

I think we've plainly established that banking is not in the player's best interest (in terms of expected value) when the probability of an individual win is 2/3; the "official" expected value is different from the answer given, and I welcome any criticism/suggestions regarding the "official" answer.

Posted by Charlie on 2020-12-31 07:36:41