The volume of the tank is:
V = l × w × h
V = 60 cm × 40 cm × 30 cm
V = 72,000 cm³
The volume of water in the tank is:
Vwater = l × w × hwater
Vwater = 60 cm × 40 cm × 18 cm
Vwater = 43,200 cm³
To find out how much more water is needed to completely fill the tank, we subtract the volume of water in the tank from the volume of the tank:
Vneeded = V - Vwater
Vneeded = 72,000 cm³ - 43,200 cm³
Vneeded = 28,800 cm³
Therefore, 28,800 cubic centimetres of water are needed to completely fill the tank.