The figure shows an empty rectangular tank with a capacity of 42 ℓ. The tank has a height of 30 cm. Tap L filled the tank at a rate of 2.3 ℓ per minute. Tap M drained water from the tank at a rate of 1.2 ℓ per minute. Both taps were turned on for 10 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 =
4200030 = 1400 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 2.3 - 1.2
= 1.1 ℓ
Volume of water that filled the tank in 10 minutes when both taps were turned on
= 10 x 1.1
= 11 ℓ
Volume of water needed to fill the tank
= 42 - 11
= 31 ℓ
Answer(s): (a) 1400 cm
2; (b) 31 ℓ