The figure shows an empty rectangular tank with a capacity of 54 ℓ. The tank has a height of 20 cm. Tap Y filled the tank at a rate of 2.8 ℓ per minute. Tap Z drained water from the tank at a rate of 1.4 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
54 ℓ = 54 x 1000 = 54000 mℓ
Base area of the tank
=
Volumeheight =
5400020 = 2700 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 2.8 - 1.4
= 1.4 ℓ
Volume of water that filled the tank in 12 minutes when both taps were turned on
= 12 x 1.4
= 16.8 ℓ
Volume of water needed to fill the tank
= 54 - 16.8
= 37.2 ℓ
Answer(s): (a) 2700 cm
2; (b) 37.2 ℓ