PSLE Water could flow out of a tank through tap A and tap B. At first, Sam turned on tap A. After some time, he also turned on tap B so that more water flowed out. Later, he turned off both taps at the same time. The line graph shows the volume of water in the tank from 17 00 to 17 32
- What was the rate of flow of water from tap A in litres per minute?
- How many litres of water flowed out of the tank throughout the period when both taps were turned on?
- What was the rate of flow of water from tap B in litres per minute?
(a)
Volume of the tank
At 17 00: 107 ℓ
At 17 08: 101 ℓ
At 17 16: 91 ℓ
At 17 24: 81 ℓ
At 17 32: 81 ℓ
Only Tap A was turned on from 17 00 to 17 08.
Decrease in the volume of water from 17 00 to 17 08
= 107 - 101
= 6 ℓ
Rate of flow of water from Tap A
= 6 ÷ 8
= 0.75 ℓ /min
(b)
Both taps were turned off at 17 24.
Volume of water that flowed out when both taps were turned on
= 101 - 81
= 20 ℓ
(c)
Tap A and Tap B were turned on from 17 08 to 17 24 for a duration of 16 min.
Volume of water that flowed out from Tap A in 16 min
= 16 x 0.75
= 12 ℓ
Volume of water that flowed out from Tap B in 16 min
= 20 - 12
= 8 ℓ
Rate of water from Tap B
= 8 ÷ 16
= 0.5 ℓ/min
Answer(s): (a) 0.75 ℓ/min; (b) 20 ℓ ; (c) 0.5 ℓ/min