Arectangular container 20 cm long and 15 cm wide contains sone water. when an iron ball was put in the water level rose by 3cm, find the the volume of the iron ball

Given that an object will always displace the same amount of water that its mass is, the ball has a volume of 900cm^3. The displacement method. You get this by multiplying 20 x 15 (the lengths and widths) and multiply it by 3 (the height the water rose) to find the volume.

Volume of rectangular is 20x15xh where h= height.
V1 = 300h
If the water level rose by 3, this multiplies the volume by 3.
V2 = V1x3 = 900h
V2-V1 = 600h which must be the volume of the ball.