Red or Blue?

Red or Blue?

Try out this famous problem! This problem is a staple in many textbooks as it can be solved in many different ways, each involving a different concept. It’s so important that a variant of it even appeared in the H3 Mathematics paper last year.

Have a go! The answer will be released next week.

2n dots are placed around the outside of the circle at distinct points. n of them are coloured red and the remaining n are coloured blue. Going around the circle clockwise, you keep a count of how many red and blue dots each you have passed. Prove that there is a starting point at which you go around the circle clockwise without ever having, at any point in the journey, encountered more red dots than blue dots.

Solution using Extremal Principle:

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