The figure shows a container made up of 3 sections. Cuboid H with a square base of side 25 cm and height 42 cm. Cube J with a side of 12 cm. Cuboid K that is 76 cm by 21 cm by 48 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 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
= 12 x 12 x 12
= 1728 cm³ 

Volume of K
= 76 x 21 x 48
= 76608 cm³ 

1 ℓ = 1000 cm³ 
2.8 ℓ = 2800 cm³ 

Net increase in volume per minute
= 2800 - 1000
= 1800 cm³/min

Height of H to be filled with water
= 66 - (48 + 12)
= 6 cm

Volume of water in H
= 25 x 25 x 6
= 3750 cm³ 

Volume of water in K, J and part of H
= 76608 + 1728 + 3750
= 82086 cm³ 

Time taken to reach height
= 82086 ÷ 1800
≈ 46 min (Correct to nearest whole number)

Answer(s): 46 min