The figure shows an empty rectangular tank with a capacity of 45 ℓ. The tank has a height of 15 cm. Tap D filled the tank at a rate of 2.8 ℓ per minute. Tap E drained water from the tank at a rate of 1.3 ℓ per minute. Both taps were turned on for 25 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 =
4500015 = 3000 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 2.8 - 1.3
= 1.5 ℓ
Volume of water that filled the tank in 25 minutes when both taps were turned on
= 25 x 1.5
= 37.5 ℓ
Volume of water needed to fill the tank
= 45 - 37.5
= 7.5 ℓ
Answer(s): (a) 3000 cm
2; (b) 7.5 ℓ