The figure shows a container made up of 3 sections. Cuboid A with a square base of side 14 cm and height 23 cm. Cube B with a side of 15 cm. Cuboid C that is 67 cm by 28 cm by 42 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 70 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of B
= 15 x 15 x 15
= 3375 cm³ 

Volume of C
= 67 x 28 x 42
= 78792 cm³ 

1 ℓ = 1000 cm³ 
2.9 ℓ = 2900 cm³ 

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

Height of A to be filled with water
= 70 - (42 + 15)
= 13 cm

Volume of water in A
= 14 x 14 x 13
= 2548 cm³ 

Volume of water in C, B and part of A
= 78792 + 3375 + 2548
= 84715 cm³ 

Time taken to reach height
= 84715 ÷ 1900
≈ 45 min (Correct to nearest whole number)

Answer(s): 45 min