6 identical 10-cm cubes are placed in an empty rectangular tank of length 90 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 12 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 6 cubes
= 6 x 1000
= 6000 cm³ 

1 ℓ = 1000 mℓ
10 ℓ = 10000 mℓ

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

Volume of ³₅ of the tank
= 120000 + 6000
= 126000 mℓ

Volume of the tank
= 126000 ÷ ³₅
= 126000 x ⁵₃
= 210000 mℓ

Base area
= 90 x 27
= 2430 cm² 

Height of the tank
= 210000 ÷ 2430
≈ 86.4 cm

Answer(s): 86.4 cm