Practice variation 2 of 3
Pigeonhole principle — Four from nine
Your question
Each of students chooses electives from . Show at least students share the same combination.
This practice question was inspired by Question 12(c) in the 2020 NSW HSC Mathematics Extension 1 examination, © NESA. It is an original TestMum variation that practises the same mathematical idea, not an official NESA question.
Before you check
- Have you stated every choice or assumption?
- Can another student follow each line?
- Did you verify the final result independently?