### Jewellery Boxes

Can you find the value of the jewels?

### Average Discovery

Find the missing number if the mean, median and mode are all the same.

### Algebraic Average

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

# Equal Means

##### Age 14 to 16 Short Challenge Level:

What value of $x$ makes the mean of the first three numbers in this list equal to the mean of the last four?$$15\qquad 5 \qquad x \qquad 7 \qquad 9 \qquad 17 \qquad$$

This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.