The mean of three numbers x, y and z is x. What is the mean of y and z?

From the mean of 64 numbers, and the mean of the first 36 of these numbers, can you work out the mean of the last 28 numbers?

When a jewel worth £5000 is transferred from one box to another, the average value of the jewels in both boxes increases. What is the total value of all the jewels?

Helen has two stables. When she moved her favourite pony from the second stable to the first, the average value of the horses in each stable increased by £10,000. What is the total value of all the ponies?

The median of a set of five positive integers is one more than the mode and one less than the mean. Can you find the largest range possible?

If some of the audience fell asleep for some of this talk, what was the average proportion of the talk that people heard?