The figure shows a container made up of 3 sections. Cuboid V with a square base of side 4 cm and height 34 cm. Cube W with a side of 14 cm. Cuboid X that is 79 cm by 13 cm by 43 cm. Water from a tap above flows down at a rate of 2.8 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
= 14 x 14 x 14
= 2744 cm³ 

Volume of X
= 79 x 13 x 43
= 44161 cm³ 

2 ℓ = 2000 cm³ 
2.8 ℓ = 2800 cm³ 

Net increase in volume per minute
= 2800 - 2000
= 800 cm³/min

Height of V to be filled with water
= 68 - (43 + 14)
= 11 cm

Volume of water in V
= 4 x 4 x 11
= 176 cm³ 

Volume of water in X, W and part of V
= 44161 + 2744 + 176
= 47081 cm³ 

Time taken to reach height
= 47081 ÷ 800
≈ 59 min (Correct to nearest whole number)

Answer(s): 59 min