How mean?
I recently set a class the following puzzle: “Write down four positive whole numbers less than 100 and then write down their average: choose the original numbers so that overall the five numbers written down use each of the digits 1 to 9 exactly once.”
Three Scandinavian lads in the class were successful. Hola came up with 9, 15, 36 and 48, with average 27. Frack was more cunning – his average was not a whole number – it involved a fraction in its simplest form, like 27¾. Dessie was devious, too, and his average, which was lower than Frack’s, was not a whole number – it involved decimals, like 16.25.
What averages did Frack and Dessie write?
WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 30 November. The Editor’s decision is final. Please send entries to Enigma 1670, Â鶹´«Ã½, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address).
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Answer to 1664 Summer sextet: P=1, A=2, Y=3, E=6, R=8, S=9
The winner Ellen Macpherson of Edinburgh, UK
