The figure shows a container made up of 3 sections. Cuboid V with a square base of side 25 cm and height 48 cm. Cube W with a side of 17 cm. Cuboid X that is 80 cm by 28 cm by 44 cm. Water from a tap above flows down at a rate of 2.2 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 68 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of W
= 17 x 17 x 17
= 4913 cm³ 

Volume of X
= 80 x 28 x 44
= 98560 cm³ 

2 ℓ = 2000 cm³ 
2.2 ℓ = 2200 cm³ 

Net increase in volume per minute
= 2200 - 2000
= 200 cm³/min

Height of V to be filled with water
= 68 - (44 + 17)
= 7 cm

Volume of water in V
= 25 x 25 x 7
= 4375 cm³ 

Volume of water in X, W and part of V
= 98560 + 4913 + 4375
= 107848 cm³ 

Time taken to reach height
= 107848 ÷ 200
≈ 539 min (Correct to nearest whole number)

Answer(s): 539 min