The figure shows an empty rectangular tank with a capacity of 30 ℓ. The tank has a height of 15 cm. Tap Y filled the tank at a rate of 3.1 ℓ per minute. Tap Z drained water from the tank at a rate of 1.6 ℓ per minute. Both taps were turned on for 9 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
30 ℓ = 30 x 1000 = 30000 mℓ
Base area of the tank
=
Volumeheight =
3000015 = 2000 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.1 - 1.6
= 1.5 ℓ
Volume of water that filled the tank in 9 minutes when both taps were turned on
= 9 x 1.5
= 13.5 ℓ
Volume of water needed to fill the tank
= 30 - 13.5
= 16.5 ℓ
Answer(s): (a) 2000 cm
2; (b) 16.5 ℓ