The figure shows an empty rectangular tank with a capacity of 65 ℓ. The tank has a height of 25 cm. Tap H filled the tank at a rate of 3 ℓ per minute. Tap J drained water from the tank at a rate of 1.5 ℓ per minute. Both taps were turned on for 20 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
65 ℓ = 65 x 1000 = 65000 mℓ
Base area of the tank
=
Volumeheight =
6500025 = 2600 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 3 - 1.5
= 1.5 ℓ
Volume of water that filled the tank in 20 minutes when both taps were turned on
= 20 x 1.5
= 30 ℓ
Volume of water needed to fill the tank
= 65 - 30
= 35 ℓ
Answer(s): (a) 2600 cm
2; (b) 35 ℓ