The figure shows an empty rectangular tank with a capacity of 36 ℓ. The tank has a height of 30 cm. Tap C filled the tank at a rate of 3.1 ℓ per minute. Tap D drained water from the tank at a rate of 1.8 ℓ per minute. Both taps were turned on for 24 minutes and then turned off.
- What is the base area of the tank?
- After both taps were turned off, how much more water is needed to fill the tank completely? Give your answer in litres.
(a)
1 ℓ = 1000 mℓ
36 ℓ = 36 x 1000 = 36000 mℓ
Base area of the tank
=
Volumeheight =
3600030 = 1200 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.1 - 1.8
= 1.3 ℓ
Volume of water that filled the tank in 24 minutes when both taps were turned on
= 24 x 1.3
= 31.2 ℓ
Volume of water needed to fill the tank
= 36 - 31.2
= 4.8 ℓ
Answer(s): (a) 1200 cm
2; (b) 4.8 ℓ