7 identical 9-cm cubes are placed in an empty rectangular tank of length 74 cm and width 22 cm. The tank is then filled with water from a tap flowing at a rate of 5 litres per minute. It takes 11 minutes to fill up ¹₂ of the tank. What is the height of the tank? Correct your answer to 1 decimal place.
Volume of 1 cube
= 9 x 9 x 9
= 729 cm³ 

Volume of 7 cubes
= 7 x 729
= 5103 cm³ 

1 ℓ = 1000 mℓ
5 ℓ = 5000 mℓ

Volume of water in the tank
= 11 x 5000
= 55000 mℓ

Volume of ¹₂ of the tank
= 55000 + 5103
= 60103 mℓ

Volume of the tank
= 60103 ÷ ¹₂
= 60103 x ²₁
= 120206 mℓ

Base area
= 74 x 22
= 1628 cm² 

Height of the tank
= 120206 ÷ 1628
≈ 73.8 cm

Answer(s): 73.8 cm