5 identical 10-cm cubes are placed in an empty rectangular tank of length 78 cm and width 24 cm. The tank is then filled with water from a tap flowing at a rate of 5 litres per minute. It takes 14 minutes to fill up ³₅ of the tank. What is the height of the tank? Correct your answer to 1 decimal place.
Volume of 1 cube
= 10 x 10 x 10
= 1000 cm³ 

Volume of 5 cubes
= 5 x 1000
= 5000 cm³ 

1 ℓ = 1000 mℓ
5 ℓ = 5000 mℓ

Volume of water in the tank
= 14 x 5000
= 70000 mℓ

Volume of ³₅ of the tank
= 70000 + 5000
= 75000 mℓ

Volume of the tank
= 75000 ÷ ³₅
= 75000 x ⁵₃
= 125000 mℓ

Base area
= 78 x 24
= 1872 cm² 

Height of the tank
= 125000 ÷ 1872
≈ 66.8 cm

Answer(s): 66.8 cm