The figure shows a container made up of 3 sections. Cuboid K with a square base of side 9 cm and height 23 cm. Cube L with a side of 15 cm. Cuboid M that is 73 cm by 24 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 1 litre per minute. How long did it take to fill up the container to a height of 63 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of L
= 15 x 15 x 15
= 3375 cm³ 

Volume of M
= 73 x 24 x 41
= 71832 cm³ 

1 ℓ = 1000 cm³ 
2.2 ℓ = 2200 cm³ 

Net increase in volume per minute
= 2200 - 1000
= 1200 cm³/min

Height of K to be filled with water
= 63 - (41 + 15)
= 7 cm

Volume of water in K
= 9 x 9 x 7
= 567 cm³ 

Volume of water in M, L and part of K
= 71832 + 3375 + 567
= 75774 cm³ 

Time taken to reach height
= 75774 ÷ 1200
≈ 63 min (Correct to nearest whole number)

Answer(s): 63 min