Copyright © University of Cambridge. All rights reserved.

'The Mean Problem' printed from https://nrich.maths.org/

Show menu



four unknown numbers


There are four unknown numbers.

The mean of the first two numbers is 4.

The mean of the first three numbers is 9.

The mean of all four numbers is 15.

If one of the four numbers is 2, what are the others?


You can find more short problems, arranged by curriculum topic, in our short problems collection.