The figure shows an empty rectangular tank with a capacity of 39 ℓ. The tank has a height of 30 cm. Tap J filled the tank at a rate of 3.1 ℓ per minute. Tap K drained water from the tank at a rate of 1.9 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
39 ℓ = 39 x 1000 = 39000 mℓ
Base area of the tank
=
Volumeheight =
3900030 = 1300 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3.1 - 1.9
= 1.2 ℓ
Volume of water that filled the tank in 27 minutes when both taps were turned on
= 27 x 1.2
= 32.4 ℓ
Volume of water needed to fill the tank
= 39 - 32.4
= 6.6 ℓ
Answer(s): (a) 1300 cm
2; (b) 6.6 ℓ