The figure shows an empty rectangular tank with a capacity of 84 ℓ. The tank has a height of 28 cm. Tap R filled the tank at a rate of 3.1 ℓ per minute. Tap S drained water from the tank at a rate of 1.2 ℓ per minute. Both taps were turned on for 22 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
84 ℓ = 84 x 1000 = 84000 mℓ
Base area of the tank
=
Volumeheight =
8400028 = 3000 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.1 - 1.2
= 1.9 ℓ
Volume of water that filled the tank in 22 minutes when both taps were turned on
= 22 x 1.9
= 41.8 ℓ
Volume of water needed to fill the tank
= 84 - 41.8
= 42.2 ℓ
Answer(s): (a) 3000 cm
2; (b) 42.2 ℓ