The figure shows an empty rectangular tank with a capacity of 36 ℓ. The tank has a height of 15 cm. Tap N filled the tank at a rate of 2.9 ℓ per minute. Tap P drained water from the tank at a rate of 1.2 ℓ per minute. Both taps were turned on for 7 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
36 ℓ = 36 x 1000 = 36000 mℓ
Base area of the tank
=
Volumeheight =
3600015 = 2400 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 2.9 - 1.2
= 1.7 ℓ
Volume of water that filled the tank in 7 minutes when both taps were turned on
= 7 x 1.7
= 11.9 ℓ
Volume of water needed to fill the tank
= 36 - 11.9
= 24.1 ℓ
Answer(s): (a) 2400 cm
2; (b) 24.1 ℓ