The figure shows a container made up of 3 sections. Cuboid L with a square base of side 14 cm and height 49 cm. Cube M with a side of 14 cm. Cuboid N that is 80 cm by 16 cm by 41 cm. Water from a tap above flows down at a rate of 2.5 litres per minute while water is drained out from the bottom at a rate of 1 litre per minute. How long did it take to fill up the container to a height of 65 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of M
= 14 x 14 x 14
= 2744 cm³ 

Volume of N
= 80 x 16 x 41
= 52480 cm³ 

1 ℓ = 1000 cm³ 
2.5 ℓ = 2500 cm³ 

Net increase in volume per minute
= 2500 - 1000
= 1500 cm³/min

Height of L to be filled with water
= 65 - (41 + 14)
= 10 cm

Volume of water in L
= 14 x 14 x 10
= 1960 cm³ 

Volume of water in N, M and part of L
= 52480 + 2744 + 1960
= 57184 cm³ 

Time taken to reach height
= 57184 ÷ 1500
≈ 38 min (Correct to nearest whole number)

Answer(s): 38 min