The figure shows a container made up of 3 sections. Cuboid F with a square base of side 4 cm and height 30 cm. Cube G with a side of 13 cm. Cuboid H that is 77 cm by 14 cm by 41 cm. Water from a tap above flows down at a rate of 3.4 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 61 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of G
= 13 x 13 x 13
= 2197 cm³ 

Volume of H
= 77 x 14 x 41
= 44198 cm³ 

2 ℓ = 2000 cm³ 
3.4 ℓ = 3400 cm³ 

Net increase in volume per minute
= 3400 - 2000
= 1400 cm³/min

Height of F to be filled with water
= 61 - (41 + 13)
= 7 cm

Volume of water in F
= 4 x 4 x 7
= 112 cm³ 

Volume of water in H, G and part of F
= 44198 + 2197 + 112
= 46507 cm³ 

Time taken to reach height
= 46507 ÷ 1400
≈ 33 min (Correct to nearest whole number)

Answer(s): 33 min