The figure shows a container made up of 3 sections. Cuboid V with a square base of side 9 cm and height 43 cm. Cube W with a side of 13 cm. Cuboid X that is 63 cm by 26 cm by 43 cm. Water from a tap above flows down at a rate of 3.2 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 67 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of W
= 13 x 13 x 13
= 2197 cm³ 

Volume of X
= 63 x 26 x 43
= 70434 cm³ 

2 ℓ = 2000 cm³ 
3.2 ℓ = 3200 cm³ 

Net increase in volume per minute
= 3200 - 2000
= 1200 cm³/min

Height of V to be filled with water
= 67 - (43 + 13)
= 11 cm

Volume of water in V
= 9 x 9 x 11
= 891 cm³ 

Volume of water in X, W and part of V
= 70434 + 2197 + 891
= 73522 cm³ 

Time taken to reach height
= 73522 ÷ 1200
≈ 61 min (Correct to nearest whole number)

Answer(s): 61 min