The figure shows an empty rectangular tank with a capacity of 70 ℓ. The tank has a height of 25 cm. Tap L filled the tank at a rate of 3.6 ℓ per minute. Tap M drained water from the tank at a rate of 1.7 ℓ per minute. Both taps were turned on for 27 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
70 ℓ = 70 x 1000 = 70000 mℓ
Base area of the tank
=
Volumeheight =
7000025 = 2800 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.6 - 1.7
= 1.9 ℓ
Volume of water that filled the tank in 27 minutes when both taps were turned on
= 27 x 1.9
= 51.3 ℓ
Volume of water needed to fill the tank
= 70 - 51.3
= 18.7 ℓ
Answer(s): (a) 2800 cm
2; (b) 18.7 ℓ