4 identical 7-cm cubes are placed in an empty rectangular tank of length 73 cm and width 27 cm. The tank is then filled with water from a tap flowing at a rate of 10 litres per minute. It takes 9 minutes to fill up ²₃ of the tank. What is the height of the tank? Correct your answer to 1 decimal place.
Volume of 1 cube
= 7 x 7 x 7
= 343 cm³ 

Volume of 4 cubes
= 4 x 343
= 1372 cm³ 

1 ℓ = 1000 mℓ
10 ℓ = 10000 mℓ

Volume of water in the tank
= 9 x 10000
= 90000 mℓ

Volume of ²₃ of the tank
= 90000 + 1372
= 91372 mℓ

Volume of the tank
= 91372 ÷ ²₃
= 91372 x ³₂
= 137058 mℓ

Base area
= 73 x 27
= 1971 cm² 

Height of the tank
= 137058 ÷ 1971
≈ 69.5 cm

Answer(s): 69.5 cm