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IMSO 2011 International Mathematics — Exploration Question 5

IMSO Maths · IMSO 2011 International Mathematics — Exploration

Question 5

A dartboard is divided into 20 numbered sectors. Each turn uses 3 darts. A bull (smallest central circle) scores 50; the surrounding half-bull ring scores 25. The unshaded part of a sector scores its number, the outer gray ring doubles it, and the middle gray ring triples it. The black outer area scores 0. The illustrated darts score $25+3\times13+12=76$.

(a) Ruthee scores 137 with two triples and one single, neither bull nor half-bull. Find all ways.

(b) Archie scores 137 with two triples and a double. Find all ways.

(c) Archie throws three darts, each scoring a double or triple. What total scores are impossible?

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