You have four jugs of 9, 7, 4 and 2 litres capacity. The 9 litre jug is full of wine, the others are empty.
Can you divide the wine into three equal quantities?
Can you do it in different ways?

You have three jugs one of which is full and holds 8 litres. The capacity of other jugs is not known. But, it is known that when using them every whole number quantity from 1 litre to 8 litres can be accurately measured out.
What could be the capacities of the 2 other jugs?
How would you measure all the whole number quantities from 1 to 8 litres?