4 identical 4-cm cubes are placed in an empty rectangular tank of length 70 cm and width 21 cm. The tank is then filled with water from a tap flowing at a rate of 5 litres per minute. It takes 10 minutes to fill up ¹₄ of the tank. What is the height of the tank? Correct your answer to 1 decimal place.
Volume of 1 cube
= 4 x 4 x 4
= 64 cm³ 

Volume of 4 cubes
= 4 x 64
= 256 cm³ 

1 ℓ = 1000 mℓ
5 ℓ = 5000 mℓ

Volume of water in the tank
= 10 x 5000
= 50000 mℓ

Volume of ¹₄ of the tank
= 50000 + 256
= 50256 mℓ

Volume of the tank
= 50256 ÷ ¹₄
= 50256 x ⁴₁
= 201024 mℓ

Base area
= 70 x 21
= 1470 cm² 

Height of the tank
= 201024 ÷ 1470
≈ 136.8 cm

Answer(s): 136.8 cm