The figure shows a tank made up of 3 sections. Cuboid W with a square base of side 14 cm and height 50 cm. Cube X with a side of 12 cm. Cuboid Y that is 61 cm by 22 cm by 41 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 69 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of X
= 12 x 12 x 12
= 1728 cm³ 

Volume of Y
= 61 x 22 x 41
= 55022 cm³ 

2 ℓ = 2000 cm³ 
2.2 ℓ = 2200 cm³ 

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

Height of W to be filled with water
= 69 - (41 + 12)
= 16 cm

Volume of water in W
= 14 x 14 x 16
= 3136 cm³ 

Volume of water in Y, X and part of W
= 55022 + 1728 + 3136
= 59886 cm³ 

Time taken to reach height
= 59886 ÷ 200
≈ 299 min (Correct to nearest whole number)

Answer(s): 299 min