The figure shows a container made up of 3 sections. Cuboid C with a square base of side 25 cm and height 38 cm. Cube D with a side of 14 cm. Cuboid E that is 64 cm by 17 cm by 44 cm. Water from a tap above flows down at a rate of 3.5 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 container to a height of 69 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of D
= 14 x 14 x 14
= 2744 cm³ 

Volume of E
= 64 x 17 x 44
= 47872 cm³ 

2 ℓ = 2000 cm³ 
3.5 ℓ = 3500 cm³ 

Net increase in volume per minute
= 3500 - 2000
= 1500 cm³/min

Height of C to be filled with water
= 69 - (44 + 14)
= 11 cm

Volume of water in C
= 25 x 25 x 11
= 6875 cm³ 

Volume of water in E, D and part of C
= 47872 + 2744 + 6875
= 57491 cm³ 

Time taken to reach height
= 57491 ÷ 1500
≈ 38 min (Correct to nearest whole number)

Answer(s): 38 min