The figure shows a tank ²₅ filled with water. The tank is made up of two cuboids. The top cuboid has a square base of length 30 cm and height of 21 cm. The bottom cuboid has a square base of length 10 cm and height 9 cm. Find the height of the water level from the base of the tank.
Volume of the top cuboid
= 30 x 30 x 21
= 18900 cm³ 

Volume of the bottom cuboid
= 10 x 10 x 9
= 900 cm³ 

Total volume
= 18900 + 900
= 19800 cm³ 

1 tank = 19800 cm^3 
2₅ tank = 19800 x ²₅ = 7920 cm³ 

Volume of water in the top cuboid
= 7920 - 900
= 7020 cm³ 

Base Area of the top cuboid
= 30 x 30
= 900 cm² 

Height of water in the top cuboid
= 7020 ÷ 900
= 7.8 cm

Height of water from base
= 7.8 + 9
= 16.8 cm

Answer(s): 16.8 cm