MathDB
Rock paper scissors

Source:

April 28, 2022

Problem Statement

Ethan Song and Bryan Guo are playing an unfair game of rock-paper-scissors. In any game, Ethan has a 2/5 chance to win, 2/5 chance to tie, and 1/5 chance to lose. How many games is Ethan expected to win before losing?
2022 CCA Math Bonanza Lightning Round 4.3