A rectangular tank measuring 150 cm by 40 cm by 110 cm is 50% filled with water. 9 identical tanks of water that are completely filled are then scooped out from it. The water level drops to 40 cm. The remaining amount of water in the tank is later poured into a container that contains 30 litres of water. The water is then drained out through a tap found at the bottom of the container at 20 litres per minute.

1. What is the capacity of each pail? Answer in litres.
2. 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 
= 110 x 50%
= 55 cm

Difference in height when 9 tanks were scooped out
= 55 - 40
= 15 cm

Volume of 9 tanks
= 150 x 40 x 15
= 90000 cm³ 

Volume of 1 tank 
= 90000 ÷ 9
= 10000 mℓ
= 10 ℓ

(b)
Remaining water in the tank 
= 150 x 40 x 40
= 240000 cm³

30 ℓ = 30000 mℓ

Total volume of water to drain
= 240000 + 30000
= 270000 mℓ

20 ℓ = 20000 mℓ

Time taken to drain the water
= 270000 ÷ 20000
= 13.5 min

Answer(s): (a) 10 ℓ; (b) 13.5 min