The figure shows a container made up of 3 sections. Cuboid N with a square base of side 4 cm and height 22 cm. Cube P with a side of 11 cm. Cuboid Q that is 80 cm by 18 cm by 42 cm. Water from a tap above flows down at a rate of 3.4 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 59 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of P
= 11 x 11 x 11
= 1331 cm³ 

Volume of Q
= 80 x 18 x 42
= 60480 cm³ 

2 ℓ = 2000 cm³ 
3.4 ℓ = 3400 cm³ 

Net increase in volume per minute
= 3400 - 2000
= 1400 cm³/min

Height of N to be filled with water
= 59 - (42 + 11)
= 6 cm

Volume of water in N
= 4 x 4 x 6
= 96 cm³ 

Volume of water in Q, P and part of N
= 60480 + 1331 + 96
= 61907 cm³ 

Time taken to reach height
= 61907 ÷ 1400
≈ 44 min (Correct to nearest whole number)

Answer(s): 44 min