The figure shows a container made up of 3 sections. Cuboid A with a square base of side 4 cm and height 30 cm. Cube B with a side of 11 cm. Cuboid C that is 78 cm by 30 cm by 45 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 70 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of B
= 11 x 11 x 11
= 1331 cm³ 

Volume of C
= 78 x 30 x 45
= 105300 cm³ 

2 ℓ = 2000 cm³ 
2.7 ℓ = 2700 cm³ 

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

Height of A to be filled with water
= 70 - (45 + 11)
= 14 cm

Volume of water in A
= 4 x 4 x 14
= 224 cm³ 

Volume of water in C, B and part of A
= 105300 + 1331 + 224
= 106855 cm³ 

Time taken to reach height
= 106855 ÷ 700
≈ 153 min (Correct to nearest whole number)

Answer(s): 153 min