The figure shows an empty rectangular tank with a capacity of 45 ℓ. The tank has a height of 30 cm. Tap Q filled the tank at a rate of 3.1 ℓ per minute. Tap R drained water from the tank at a rate of 1.4 ℓ per minute. Both taps were turned on for 9 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
45 ℓ = 45 x 1000 = 45000 mℓ
Base area of the tank
=
Volumeheight =
4500030 = 1500 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.1 - 1.4
= 1.7 ℓ
Volume of water that filled the tank in 9 minutes when both taps were turned on
= 9 x 1.7
= 15.3 ℓ
Volume of water needed to fill the tank
= 45 - 15.3
= 29.7 ℓ
Answer(s): (a) 1500 cm
2; (b) 29.7 ℓ