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?

(In reply to Solution by Senthil Kumar)

No, the probability of winning a game can't be 1/10 because you have 4 tries. Better calculate the chance of failure ((9/10)^4) and substract it from 1 like in the previous solutions.

Edit: You are too fast for me, Brian! ;)
Edited on September 18, 2003, 7:03 pm

Posted by abc on 2003-09-18 19:02:40