Library / /394 of 472

, 2011

Combinatorics Difficulty 3.0 AMC 10/12 Find the answer Canada

A gumball machine that randomly dispenses one gumball at a time contains $13$ red, $5$ blue, $1$ white, and $9$ green gumballs. What is the least number of gumballs that Wally must buy to guarantee that he receives $3$ gumballs of the same colour?

(A) $6$ (B) $9$ (C) $4$ (D) $7$ (E) $8$

Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.