PSLE
At first, Containers W, X and Y contained water as shown in Figure 1. Some water from W and X was poured into Container Y without spilling. The amount of water left in Container W and X is shown in Figure 2. What would be the amount of water in Container Y?
1 ℓ = 1000 mℓ

Container W 
10 intervals = 500
1 interval = 500 ÷ 10 = 50

Decrease in the volume of water in Container W
= 2 intervals of Container W
= 2 x 50
= 100 mℓ

Container X
10 intervals = 200
1 interval = 200 ÷ 10 = 20

Decrease in the volume of water in Container X
= 3 intervals of Container X
= 3 x 20 
= 60 mℓ

Container Y
10 intervals = 1000
1 interval = 1000 ÷ 10 = 100

Volume of water in Container Y at first
= 5 intervals of Container Y
= 5 x 100
= 500 mℓ

Total decrease in volume of water in Containers W and X
= 100 + 60
= 160 mℓ

Volume of water in Container Y in the end
= 500 + 160
= 660 mℓ

Answer(s): 660 mℓ