The figure shows an empty rectangular tank with a capacity of 72 ℓ. The tank has a height of 30 cm. Tap V filled the tank at a rate of 3.2 ℓ per minute. Tap W drained water from the tank at a rate of 1.9 ℓ per minute. Both taps were turned on for 29 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
72 ℓ = 72 x 1000 = 72000 mℓ
Base area of the tank
=
Volumeheight =
7200030 = 2400 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.2 - 1.9
= 1.3 ℓ
Volume of water that filled the tank in 29 minutes when both taps were turned on
= 29 x 1.3
= 37.7 ℓ
Volume of water needed to fill the tank
= 72 - 37.7
= 34.3 ℓ
Answer(s): (a) 2400 cm
2; (b) 34.3 ℓ