The figure shows a container made up of 3 sections. Cuboid X with a square base of side 14 cm and height 49 cm. Cube Y with a side of 15 cm. Cuboid Z that is 60 cm by 25 cm by 41 cm. Water from a tap above flows down at a rate of 2.6 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 68 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of Y
= 15 x 15 x 15
= 3375 cm³ 

Volume of Z
= 60 x 25 x 41
= 61500 cm³ 

1 ℓ = 1000 cm³ 
2.6 ℓ = 2600 cm³ 

Net increase in volume per minute
= 2600 - 1000
= 1600 cm³/min

Height of X to be filled with water
= 68 - (41 + 15)
= 12 cm

Volume of water in X
= 14 x 14 x 12
= 2352 cm³ 

Volume of water in Z, Y and part of X
= 61500 + 3375 + 2352
= 67227 cm³ 

Time taken to reach height
= 67227 ÷ 1600
≈ 42 min (Correct to nearest whole number)

Answer(s): 42 min