The figure shows a tank made up of 3 sections. Cuboid E with a square base of side 25 cm and height 47 cm. Cube F with a side of 11 cm. Cuboid G that is 78 cm by 22 cm by 47 cm. Water from a tap above flows down at a rate of 2.6 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 tank to a height of 65 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of F
= 11 x 11 x 11
= 1331 cm³ 

Volume of G
= 78 x 22 x 47
= 80652 cm³ 

2 ℓ = 2000 cm³ 
2.6 ℓ = 2600 cm³ 

Net increase in volume per minute
= 2600 - 2000
= 600 cm³/min

Height of E to be filled with water
= 65 - (47 + 11)
= 7 cm

Volume of water in E
= 25 x 25 x 7
= 4375 cm³ 

Volume of water in G, F and part of E
= 80652 + 1331 + 4375
= 86358 cm³ 

Time taken to reach height
= 86358 ÷ 600
≈ 144 min (Correct to nearest whole number)

Answer(s): 144 min