The figure shows a container made up of 3 sections. Cuboid W with a square base of side 25 cm and height 24 cm. Cube X with a side of 14 cm. Cuboid Y that is 62 cm by 23 cm by 43 cm. Water from a tap above flows down at a rate of 3.4 litres per minute while water is drained out from the bottom at a rate of 1 litre per minute. How long did it take to fill up the container to a height of 65 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of X
= 14 x 14 x 14
= 2744 cm³ 

Volume of Y
= 62 x 23 x 43
= 61318 cm³ 

1 ℓ = 1000 cm³ 
3.4 ℓ = 3400 cm³ 

Net increase in volume per minute
= 3400 - 1000
= 2400 cm³/min

Height of W to be filled with water
= 65 - (43 + 14)
= 8 cm

Volume of water in W
= 25 x 25 x 8
= 5000 cm³ 

Volume of water in Y, X and part of W
= 61318 + 2744 + 5000
= 69062 cm³ 

Time taken to reach height
= 69062 ÷ 2400
≈ 29 min (Correct to nearest whole number)

Answer(s): 29 min