A cubical tank of edge 30 cm contained some water to a height of 8 cm.
- Find the volume of water in the tank at first.
- A tap was then turned on for 15 minutes to fill the tank with water at a rate of 0.7 ℓ per minute. How much more water was needed to fill the tank to the brim when the tap was turned off? Leave your answer in litres.
(a)
Volume of water in the tank at first
= 30 x 30 x 8
= 7200 cm
3
(b)
Remaining height of the tank not filled with water before the tap was turned on
= 30 - 8
= 22 cm
Volume of water needed to fill the tank
= 30 x 30 x 22
= 19800 cm³
1 ℓ = 1000 mℓ
0.7 ℓ = 0.7 x 1000 = 700 mℓ
Volume of water filled by the tap in 15 min
= 15 x 700
= 10500 cm
3Volume of more water needed to fill the tank to the brim when the tap was turned off
= 19800 - 10500
= 9300 cm
3
9300 mℓ = 9300 ÷ 1000 = 9.3 ℓ
Volume of more water to fill the tank = 9.3 ℓ
Answer(s): (a) 7200 cm
3; (b) 9.3 ℓ