The figure shows an empty rectangular container with a capacity of 21 ℓ. The container has a height of 15 cm. Tap T filled the container at a rate of 3 ℓ per minute. Tap U drained water from the container 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 container?
- After both taps were turned off, how much more water is needed to fill the container completely? Give your answer in litres.
(a)
1 ℓ = 1000 mℓ
21 ℓ = 21 x 1000 = 21000 mℓ
Base area of the container
=
Volumeheight =
2100015 = 1400 cm
2 (b)
Volume of water that filled the container per minute when both taps were turned on
= 3 - 1.5
= 1.5 ℓ
Volume of water that filled the container in 9 minutes when both taps were turned on
= 9 x 1.5
= 13.5 ℓ
Volume of water needed to fill the container
= 21 - 13.5
= 7.5 ℓ
Answer(s): (a) 1400 cm
2; (b) 7.5 ℓ