PSLE
George filled a container with water using two taps. He turned on Tap Q first and after 4 minutes, he also turned on Tap R. Both taps were turned off at the same time when the container was completely filled without overflowing. The graph shows the amount of water in the container over 16 minutes.

1. What fraction of the container was filled 4 minutes after Tap Q was turned on? Express your answer in the simplest form.
2. In one minute, how many litres of water flowed from Tap R?

(a)
Capacity of the container = 42 ℓ
Volume of water in the tank after 4 minutes = 6 ℓ

Fraction of the container that was filled 4 minutes after Tap Q was turned on
= ⁶₄₂  
= ¹₇

(b) 

	Tap Q	Tap R	Total
First 4 min	6 ℓ	0 ℓ	6 ℓ
Next 6 min	9 ℓ	27 ℓ	36 ℓ

Volume of water that flowed from Tap Q and Tap R in 10 minutes = 42 ℓ

Duration that Tap R was turned on
= 10 - 4
= 6 min

Volume of water that flowed from Tap Q in 6 minutes
= ⁶₄  x 6
= 9 ℓ

Volume of water that flowed from Tap Q and Tap R in 6 minutes
= 42 - 6
= 36 ℓ

Volume of water that flowed from Tap R in 6 minutes
= 36 - 9
= 27 ℓ

Volume of water that flowed from Tap R in 1 minute
= 27 ÷ 6
= 4.5 ℓ

Answer(s): (a) ¹₇ ; (b) 4.5 ℓ