The figure shows an empty container. It is made from two cubical tanks. The tanks, Cube S and Cube T, are of sides 30 cm and 50 cm respectively. Cube S is attached to the centre of one of the sides of the Cube T. 59 litres of water is poured into the container such that water flows in to fill part of Cube S. What is the height of the water level in the container? Round off your answer to one decimal place.
Height of water in Cube T before overflow into Cube S
= (50 - 30) ÷ 2 
= 10 cm

Volume of water in the big cube before overflow into Cube T
= 50 x 50 x 10
= 25000 cm³ 

Combined base areas of Cube S and Cube T
= (30 x 30) + (50 x 50)
= 900 + 2500
= 3400 cm² 

59 ℓ = 59 x 1000 = 59000 mℓ

Volume of water after the overflow
= 59000 - 25000
= 34000 cm³ 

Height of water in Cube S
= 34000 ÷ 3400
≈ 10.0 cm

Total height of water
= 10.0 + 10
≈ 20 cm

Answer(s): 20 cm