The figure shows a container made up of 3 sections. Cuboid C with a square base of side 14 cm and height 25 cm. Cube D with a side of 14 cm. Cuboid E that is 71 cm by 12 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 1 litre per minute. How long did it take to fill up the container to a height of 63 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of D
= 14 x 14 x 14
= 2744 cm³ 

Volume of E
= 71 x 12 x 43
= 36636 cm³ 

1 ℓ = 1000 cm³ 
3.2 ℓ = 3200 cm³ 

Net increase in volume per minute
= 3200 - 1000
= 2200 cm³/min

Height of C to be filled with water
= 63 - (43 + 14)
= 6 cm

Volume of water in C
= 14 x 14 x 6
= 1176 cm³ 

Volume of water in E, D and part of C
= 36636 + 2744 + 1176
= 40556 cm³ 

Time taken to reach height
= 40556 ÷ 2200
≈ 18 min (Correct to nearest whole number)

Answer(s): 18 min