The figure shows a container made up of 3 sections. Cuboid Y with a square base of side 14 cm and height 35 cm. Cube Z with a side of 12 cm. Cuboid A that is 62 cm by 13 cm by 40 cm. Water from a tap above flows down at a rate of 2.9 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 58 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of Z
= 12 x 12 x 12
= 1728 cm³ 

Volume of A
= 62 x 13 x 40
= 32240 cm³ 

1 ℓ = 1000 cm³ 
2.9 ℓ = 2900 cm³ 

Net increase in volume per minute
= 2900 - 1000
= 1900 cm³/min

Height of Y to be filled with water
= 58 - (40 + 12)
= 6 cm

Volume of water in Y
= 14 x 14 x 6
= 1176 cm³ 

Volume of water in A, Z and part of Y
= 32240 + 1728 + 1176
= 35144 cm³ 

Time taken to reach height
= 35144 ÷ 1900
≈ 18 min (Correct to nearest whole number)

Answer(s): 18 min