The figure shows a container made up of 3 sections. Cuboid H with a square base of side 4 cm and height 45 cm. Cube J with a side of 17 cm. Cuboid K that is 77 cm by 19 cm by 44 cm. Water from a tap above flows down at a rate of 3.8 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 70 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of J
= 17 x 17 x 17
= 4913 cm³ 

Volume of K
= 77 x 19 x 44
= 64372 cm³ 

2 ℓ = 2000 cm³ 
3.8 ℓ = 3800 cm³ 

Net increase in volume per minute
= 3800 - 2000
= 1800 cm³/min

Height of H to be filled with water
= 70 - (44 + 17)
= 9 cm

Volume of water in H
= 4 x 4 x 9
= 144 cm³ 

Volume of water in K, J and part of H
= 64372 + 4913 + 144
= 69429 cm³ 

Time taken to reach height
= 69429 ÷ 1800
≈ 39 min (Correct to nearest whole number)

Answer(s): 39 min