MathDB
Alice has 4 boxes, 327 blue balls, and 2022 red balls

Source: Canada Repêchage 2022/5 CMOQR

October 13, 2022
combinatorics

Problem Statement

Alice has four boxes, 327327 blue balls, and 20222022 red balls. The blue balls are labeled 11 to 327327. Alice first puts each of the balls into a box, possibly leaving some boxes empty. Then, a random label between 11 and 327327 (inclusive) is selected, Alice finds the box the ball with the label is in, and selects a random ball from that box. What is the maximum probability that she selects a red ball?