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Problem 75

Combinatorics Difficulty 1.2 Multiple choice CEMC Cayley · Canada · 2026

Carley went for a run on May 18th. She did not go for a run on
May 19th. She continued to alternate going for a run one day with not
going for a run the following day. Between May 18th and May 25th
inclusive, how many days did she go for a run?

Pick one

Official solution

Running every second day, Carley ran on May 18, 20, 22, and 24.
Between May 18th and 25th inclusive, Carley ran on 4 days.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.