The figure shows an empty rectangular tank with a capacity of 42 ℓ. The tank has a height of 15 cm. Tap N filled the tank at a rate of 3 ℓ per minute. Tap P drained water from the tank at a rate of 1.9 ℓ per minute. Both taps were turned on for 24 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
42 ℓ = 42 x 1000 = 42000 mℓ
Base area of the tank
=
Volumeheight =
4200015 = 2800 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3 - 1.9
= 1.1 ℓ
Volume of water that filled the tank in 24 minutes when both taps were turned on
= 24 x 1.1
= 26.4 ℓ
Volume of water needed to fill the tank
= 42 - 26.4
= 15.6 ℓ
Answer(s): (a) 2800 cm
2; (b) 15.6 ℓ