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

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

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

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

Decrease in the volume of water in Container S
= 2 intervals of Container S
= 2 x 20 
= 40 mℓ

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

Volume of water in Container T at first
= 3 intervals of Container T
= 3 x 100
= 300 mℓ

Total decrease in volume of water in Containers R and S
= 100 + 40
= 140 mℓ

Volume of water in Container T in the end
= 300 + 140
= 440 mℓ

Answer(s): 440 mℓ