Two classmates play the game Rock-Paper-Scissors to decide who will pay for coffee. If there is a draw (both players show the same hand shape), then there is no decision. The game is played until there is no draw (two different shapes appear on the same game). We assume the two players each choose randomly between the 3 shapes on each game, and the players choose independently of one another. Also, the games are assumed to be independent. What is the probability that there must be at least 4 games played in total? Show your work..