The figure shows a tank made up of 3 sections. Cuboid E with a square base of side 14 cm and height 47 cm. Cube F with a side of 10 cm. Cuboid G that is 68 cm by 15 cm by 40 cm. Water from a tap above flows down at a rate of 2.4 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 63 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of F
= 10 x 10 x 10
= 1000 cm³ 

Volume of G
= 68 x 15 x 40
= 40800 cm³ 

1 ℓ = 1000 cm³ 
2.4 ℓ = 2400 cm³ 

Net increase in volume per minute
= 2400 - 1000
= 1400 cm³/min

Height of E to be filled with water
= 63 - (40 + 10)
= 13 cm

Volume of water in E
= 14 x 14 x 13
= 2548 cm³ 

Volume of water in G, F and part of E
= 40800 + 1000 + 2548
= 44348 cm³ 

Time taken to reach height
= 44348 ÷ 1400
≈ 32 min (Correct to nearest whole number)

Answer(s): 32 min