6 identical 7-cm cubes are placed in an empty rectangular tank of length 77 cm and width 23 cm. The tank is then filled with water from a tap flowing at a rate of 10 litres per minute. It takes 12 minutes to fill up ¹₅ 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 6 cubes
= 6 x 343
= 2058 cm³ 

1 ℓ = 1000 mℓ
10 ℓ = 10000 mℓ

Volume of water in the tank
= 12 x 10000
= 120000 mℓ

Volume of ¹₅ of the tank
= 120000 + 2058
= 122058 mℓ

Volume of the tank
= 122058 ÷ ¹₅
= 122058 x ⁵₁
= 610290 mℓ

Base area
= 77 x 23
= 1771 cm² 

Height of the tank
= 610290 ÷ 1771
≈ 344.6 cm

Answer(s): 344.6 cm