MathDB
2021 Spring LMT Division A Problem 28, B Problem 29

Source:

January 22, 2022
combinatorics

Problem Statement

Addison and Emerson are playing a card game with three rounds. Addison has the cards 1,31, 3, and 55, and Emerson has the cards 2,42, 4, and 66. In advance of the game, both designate each one of their cards to be played for either round one, two, or three. Cards cannot be played for multiple rounds. In each round, both show each other their designated card for that round, and the person with the higher-numbered card wins the round. The person who wins the most rounds wins the game. Let m/nm/n be the probability that Emerson wins, where mm and nn are relatively prime positive integers. Find m+nm +n.
Proposed by Ada Tsui