4th grade math problem

Here is a 4th grade math problem. I did not know the answer. who will be the smartest one here?

Colin, Kai, and Sampson are playing a dice game. Colin goes first, Kai second, and Sampson third. The first person to roll a three wins and game is oever. The dice are continuously passed in the above order until some one wins. What is the probability that Sampson wins?