The figure shows an empty rectangular tank with a capacity of 78 ℓ. The tank has a height of 30 cm. Tap H filled the tank at a rate of 2.2 ℓ per minute. Tap J drained water from the tank at a rate of 1.1 ℓ per minute. Both taps were turned on for 13 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
78 ℓ = 78 x 1000 = 78000 mℓ
Base area of the tank
=
Volumeheight =
7800030 = 2600 cm
2 (b)
Volume of water that filled the tank per minute when both taps were turned on
= 2.2 - 1.1
= 1.1 ℓ
Volume of water that filled the tank in 13 minutes when both taps were turned on
= 13 x 1.1
= 14.3 ℓ
Volume of water needed to fill the tank
= 78 - 14.3
= 63.7 ℓ
Answer(s): (a) 2600 cm
2; (b) 63.7 ℓ