The figure shows a container made up of 3 sections. Cuboid D with a square base of side 25 cm and height 39 cm. Cube E with a side of 10 cm. Cuboid F that is 70 cm by 10 cm by 48 cm. Water from a tap above flows down at a rate of 2.7 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 64 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of E
= 10 x 10 x 10
= 1000 cm³ 

Volume of F
= 70 x 10 x 48
= 33600 cm³ 

2 ℓ = 2000 cm³ 
2.7 ℓ = 2700 cm³ 

Net increase in volume per minute
= 2700 - 2000
= 700 cm³/min

Height of D to be filled with water
= 64 - (48 + 10)
= 6 cm

Volume of water in D
= 25 x 25 x 6
= 3750 cm³ 

Volume of water in F, E and part of D
= 33600 + 1000 + 3750
= 38350 cm³ 

Time taken to reach height
= 38350 ÷ 700
≈ 55 min (Correct to nearest whole number)

Answer(s): 55 min