The figure shows a tank made up of 3 sections. Cuboid C with a square base of side 4 cm and height 29 cm. Cube D with a side of 12 cm. Cuboid E that is 70 cm by 20 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 2 litre per minute. How long did it take to fill up the tank to a height of 64 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of D
= 12 x 12 x 12
= 1728 cm³ 

Volume of E
= 70 x 20 x 40
= 56000 cm³ 

2 ℓ = 2000 cm³ 
2.2 ℓ = 2200 cm³ 

Net increase in volume per minute
= 2200 - 2000
= 200 cm³/min

Height of C to be filled with water
= 64 - (40 + 12)
= 12 cm

Volume of water in C
= 4 x 4 x 12
= 192 cm³ 

Volume of water in E, D and part of C
= 56000 + 1728 + 192
= 57920 cm³ 

Time taken to reach height
= 57920 ÷ 200
≈ 290 min (Correct to nearest whole number)

Answer(s): 290 min