The figure shows a tank made up of 3 sections. Cuboid S with a square base of side 14 cm and height 34 cm. Cube T with a side of 10 cm. Cuboid U that is 60 cm by 25 cm by 42 cm. Water from a tap above flows down at a rate of 2.8 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 tank to a height of 66 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of T
= 10 x 10 x 10
= 1000 cm³ 

Volume of U
= 60 x 25 x 42
= 63000 cm³ 

1 ℓ = 1000 cm³ 
2.8 ℓ = 2800 cm³ 

Net increase in volume per minute
= 2800 - 1000
= 1800 cm³/min

Height of S to be filled with water
= 66 - (42 + 10)
= 14 cm

Volume of water in S
= 14 x 14 x 14
= 2744 cm³ 

Volume of water in U, T and part of S
= 63000 + 1000 + 2744
= 66744 cm³ 

Time taken to reach height
= 66744 ÷ 1800
≈ 37 min (Correct to nearest whole number)

Answer(s): 37 min