You look at a carnival game. The person running it says, "Just reach your hand into this bag. There are 9 yellow balls and 1 red ball in the bag. You get 4 chances to pull out the red ball. (You have to put the ball you drew back before you draw another ball.) You only have to pay one dollar to play, and you get 3 dollars if you pull out the red ball!"

Assuming the person running the game is telling the truth, and the balls only differ in color, would you expect to make a net profit or a net loss on this game?

I'm not very good at probability myself. I didn't make any more calculations than fwaff.

fwaff is right, that the chance to succeed is about 34% (0.3439).
This means that I win every third game, statistically speaking.
Losing two games costs 2$. I pay for the third game and lose another 1$. I should win this one and get 3$ in return.
After all there's no gain and no loss. You spend 3$ on average and win them back in the third game resulting in a balance.

Assuming that probability is cheating me I would probably lose money on the long run. 8)

Posted by abc on 2003-09-18 13:15:49