A hollow cylindrical pipe is 21 dm long. Its outré and inner diameters are 10 cm and 6 cm respectively. Find the volume of the copper used in making the pipe.
Given,
Length of cylinder = 21 dm = 210 cm
Outer diameter = 10 cm
Outer radius = 
Inner diameter = 6 cm
Inner radius = 
∴ Area of base = 
Volume of cylinder = 
5