You may also like

Upsetting Pitagoras

Find the smallest integer solution to the equation 1/x^2 + 1/y^2 = 1/z^2

Rudolff's Problem

A group of 20 people pay a total of £20 to see an exhibition. The admission price is £3 for men, £2 for women and 50p for children. How many men, women and children are there in the group?

Euler's Squares

Euler found four whole numbers such that the sum of any two of the numbers is a perfect square...


Age 14 to 16
Challenge Level

At a well known store they sell their own blend of coffee. They use:

Mocha costing £13 per kilogram
Kenyan costing £14 per kilogram
Brazilian costing £17 per kilogram

To make 11 kilograms of this blend of coffee costs £15 per kilogram.
This blend uses more Brazilian than Kenyan coffee.
An exact number of kilograms of each type of coffee is used.
How many kilograms of each type of coffee are used?