The figure shows an empty rectangular tank with a capacity of 18 ℓ. The tank has a height of 15 cm. Tap S filled the tank at a rate of 2.9 ℓ per minute. Tap T drained water from the tank at a rate of 1.5 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
18 ℓ = 18 x 1000 = 18000 mℓ
Base area of the tank
=
Volumeheight =
1800015 = 1200 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 2.9 - 1.5
= 1.4 ℓ
Volume of water that filled the tank in 9 minutes when both taps were turned on
= 9 x 1.4
= 12.6 ℓ
Volume of water needed to fill the tank
= 18 - 12.6
= 5.4 ℓ
Answer(s): (a) 1200 cm
2; (b) 5.4 ℓ