Australian AMC 2008 - Intermediate Question 21

Question 21

Farmer Taylor of Burra has two tanks. Water from the roof of his farmhouse is collected in a 100 kL tank and water from the roof of his barn is collected in a 25 kL tank. The collecting area of his farmhouse roof is 200 square metres while that of his barn is 80 square metres. Currently, there are 35 kL in the farmhouse tank and 13 kL in the barn tank.

Rain is forecast and he wants to collect as much water as possible. He should:

empty the barn tank into the farmhouse tank
fill the barn tank from the farmhouse tank
pump 10 kL from the farmhouse tank into the barn tank
pump 10 kL from the barn tank into the farmhouse tank
do nothing