9 identical 7-cm cubes are placed in an empty rectangular tank of length 86 cm and width 29 cm. The tank is then filled with water from a tap flowing at a rate of 10 litres per minute. It takes 13 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
= 7 x 7 x 7
= 343 cm³ 

Volume of 9 cubes
= 9 x 343
= 3087 cm³ 

1 ℓ = 1000 mℓ
10 ℓ = 10000 mℓ

Volume of water in the tank
= 13 x 10000
= 130000 mℓ

Volume of ¹₄ of the tank
= 130000 + 3087
= 133087 mℓ

Volume of the tank
= 133087 ÷ ¹₄
= 133087 x ⁴₁
= 532348 mℓ

Base area
= 86 x 29
= 2494 cm² 

Height of the tank
= 532348 ÷ 2494
≈ 213.5 cm

Answer(s): 213.5 cm