The figure shows an empty rectangular tank with a capacity of 36 ℓ. The tank has a height of 20 cm. Tap Q filled the tank at a rate of 3.4 ℓ per minute. Tap R drained water from the tank at a rate of 1.5 ℓ per minute. Both taps were turned on for 12 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 =
3600020 = 1800 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.4 - 1.5
= 1.9 ℓ
Volume of water that filled the tank in 12 minutes when both taps were turned on
= 12 x 1.9
= 22.8 ℓ
Volume of water needed to fill the tank
= 36 - 22.8
= 13.2 ℓ
Answer(s): (a) 1800 cm
2; (b) 13.2 ℓ