Figure L shows a closed rectangular tank of dimensions 40 cm by 40 cm by 90 cm with a cube of edge 25 cm glued to its bottom right corner. The tank contains 75 litres of water. Figure M shows the same rectangular tank lying on its side. Find the height of the water level, in centimetres, corrected to 2 decimal places.
Height of water under the cube in Figure M 
= 40 - 25
= 15 cm

Volume of water under the cube in Figure M 
= 90 x 40 x 15
= 54000 cm³ 

1 ℓ = 1000 
75 ℓ = 75000cm³ 

Volume of water beside the cube
= 75000 - 54000
= 21000 cm³ 

Base area of water beside the cube
= (40 x 90) - (25 x 25)
= 3600 - 625
= 2975 cm² 

Height of water level beside the cube
= 21000 ÷ 2975
≈ 7.06 cm

Height of the water level
= 7.06 + 25
≈ 32.06 cm

Answer(s): 32.06 cm