The figure shows a container made up of 3 sections. Cuboid H with a square base of side 14 cm and height 34 cm. Cube J with a side of 20 cm. Cuboid K that is 63 cm by 22 cm by 40 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 66 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of J
= 20 x 20 x 20
= 8000 cm³ 

Volume of K
= 63 x 22 x 40
= 55440 cm³ 

1 ℓ = 1000 cm³ 
3.2 ℓ = 3200 cm³ 

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

Height of H to be filled with water
= 66 - (40 + 20)
= 6 cm

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

Volume of water in K, J and part of H
= 55440 + 8000 + 1176
= 64616 cm³ 

Time taken to reach height
= 64616 ÷ 2200
≈ 29 min (Correct to nearest whole number)

Answer(s): 29 min