The figure shows an empty rectangular tank with a capacity of 54 ℓ. The tank has a height of 18 cm. Tap T filled the tank at a rate of 3.1 ℓ per minute. Tap U drained water from the tank at a rate of 1.5 ℓ per minute. Both taps were turned on for 21 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
54 ℓ = 54 x 1000 = 54000 mℓ
Base area of the tank
=
Volumeheight =
5400018 = 3000 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.1 - 1.5
= 1.6 ℓ
Volume of water that filled the tank in 21 minutes when both taps were turned on
= 21 x 1.6
= 33.6 ℓ
Volume of water needed to fill the tank
= 54 - 33.6
= 20.4 ℓ
Answer(s): (a) 3000 cm
2; (b) 20.4 ℓ