A rectangular tank measuring 150 cm by 40 cm by 120 cm is 50% filled with water. 10 identical tanks of water that are completely filled are then scooped out from it. The water level drops to 45 cm. The remaining amount of water in the tank is later poured into a container that contains 50 litres of water. The water is then drained out through a tap found at the bottom of the container at 10 litres per minute.
- What is the capacity of each pail? Answer in litres.
- How long did it take to drain the water from the container completely? Answer in terms of min.
(a)
Original height of water in the tank
= 120 x 50%
= 60 cm
Difference in height when 10 tanks were scooped out
= 60 - 45
= 15 cm
Volume of 10 tanks
= 150 x 40 x 15
= 90000 cm
3 Volume of 1 tank
= 90000 ÷ 10
= 9000 mℓ
= 9 ℓ
(b)
Remaining water in the tank
= 150 x 40 x 45
= 270000 cm
3 50 ℓ = 50000 mℓ
Total volume of water to drain
= 270000 + 50000
= 320000 mℓ
10 ℓ = 10000 mℓ
Time taken to drain the water
= 320000 ÷ 10000
= 32 min
Answer(s): (a) 9 ℓ; (b) 32 min