The figure shows a container made up of 3 sections. Cuboid W with a square base of side 4 cm and height 21 cm. Cube X with a side of 10 cm. Cuboid Y that is 61 cm by 20 cm by 40 cm. Water from a tap above flows down at a rate of 2.3 litres per minute while water is drained out from the bottom at a rate of 2 litre per minute. How long did it take to fill up the container to a height of 60 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of X
= 10 x 10 x 10
= 1000 cm³ 

Volume of Y
= 61 x 20 x 40
= 48800 cm³ 

2 ℓ = 2000 cm³ 
2.3 ℓ = 2300 cm³ 

Net increase in volume per minute
= 2300 - 2000
= 300 cm³/min

Height of W to be filled with water
= 60 - (40 + 10)
= 10 cm

Volume of water in W
= 4 x 4 x 10
= 160 cm³ 

Volume of water in Y, X and part of W
= 48800 + 1000 + 160
= 49960 cm³ 

Time taken to reach height
= 49960 ÷ 300
≈ 167 min (Correct to nearest whole number)

Answer(s): 167 min