Figure K shows a closed rectangular tank of dimensions 42 cm by 42 cm by 70 cm with a cube of edge 22 cm glued to its bottom right corner. The tank contains 75 litres of water. Figure L 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 L 
= 42 - 22
= 20 cm

Volume of water under the cube in Figure L 
= 70 x 42 x 20
= 58800 cm³ 

1 ℓ = 1000 
75 ℓ = 75000cm³ 

Volume of water beside the cube
= 75000 - 58800
= 16200 cm³ 

Base area of water beside the cube
= (42 x 70) - (22 x 22)
= 2940 - 484
= 2456 cm² 

Height of water level beside the cube
= 16200 ÷ 2456
≈ 6.60 cm

Height of the water level
= 6.60 + 22
≈ 28.6 cm

Answer(s): 28.6 cm