The figure shows a tank made up of 3 sections. Cuboid F with a square base of side 4 cm and height 24 cm. Cube G with a side of 15 cm. Cuboid H that is 76 cm by 17 cm by 40 cm. Water from a tap above flows down at a rate of 2.2 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 tank to a height of 62 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of G
= 15 x 15 x 15
= 3375 cm³ 

Volume of H
= 76 x 17 x 40
= 51680 cm³ 

1 ℓ = 1000 cm³ 
2.2 ℓ = 2200 cm³ 

Net increase in volume per minute
= 2200 - 1000
= 1200 cm³/min

Height of F to be filled with water
= 62 - (40 + 15)
= 7 cm

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

Volume of water in H, G and part of F
= 51680 + 3375 + 112
= 55167 cm³ 

Time taken to reach height
= 55167 ÷ 1200
≈ 46 min (Correct to nearest whole number)

Answer(s): 46 min