Main content

Today Puzzle #760

Puzzle No. 760– Friday 12 June

The annual fees for the Puzzle Challenge Club are £23 per person, with a special rate for senior citizens of £17. If the total amount of dues collected last year was £1500, what is the smallest number of senior citizens that belong to the club?

Today’s #PuzzleForToday has been set by Dr Steve Humble from Newcastle University

Click here for the answer

There are only 4 possible alternative ways of the club fees being £1500. The alternative with 3 senior citizens is the smallest.

Details of a possible solution.

23X + 17Y = 1500

We can re-write this equation as

X = 12 – 17n and Y = 72 + 23n

where n can take values of 0, -1, -2, -3

Q Y senior X general Senior fees General fees

0 72 12 £1224 £276

-1 49 29 £833 £667

-2 26 46 £442 £1058

-3 3 63 £51 £1449

More fiendish brain-teasers and quizzes on Â鶹¹ÙÍøÊ×Ò³Èë¿Ú Radio...