Helen has two stables, each of which initially housed three ponies.

One day, Helen decided to move her favourite pony from the small stable to the large stable. This increased the mean value of the ponies in the small stable by £10 000. To her surprise, this also increased the mean value of the ponies in the large stable by £10 000.

If her favourite pony is worth £250 000, what is the total value of all six of Helen's ponies?

This problem is taken from the UKMT Mathematical Challenges.

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