A rectangular tank 40 cm long, 20 cm wide and 30 cm high was
78 filled with water.
- What was the volume of the water in the tank in litres?
- A tap was used to drain the water from the tank at a rate of 4 ℓ per minute. The tap was turned off when the tank was 13 filled with water. How long did it take to drain the water?
(a)
Volume of water in the tank
=
78 x 40 x 20 x 30
= 21000 cm
3 1000 mℓ = 1 ℓ
21000 mℓ = 21000 ÷ 1000 = 21 ℓ
Volume of water in the tank = 21 ℓ
(b)
Volume of water in the tank in the end
=
13 x 40 x 20 x 30
= 8000 cm
3 Volume of water that was drained from the tank
= 21000 - 8000
= 13000 cm
34 ℓ = 4 x 1000 = 4000 mℓ
Time taken for the tap to drain the water
= 13000 ÷ 4000
= 3.25 min
Answer(s): (a) 21 ℓ; (b) 3.25 min