SOLUTION: Show a cylinderical casting of height 8cm and external and internal diameters 9cm and 5cm respectively.calculate the volume of metal on the casting

Question 758286: Show a cylinderical casting of height 8cm and external and internal diameters 9cm and 5cm respectively.calculate the volume of metal on the casting
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!
I assume that means an 8-cm long piece of pipe, with external and internal diameters 9cm and 5cm respectively, without a cover on either end.
Its volume would be
the volume of a solid cylinder, 8-cm tall, with a diameter of 9 cm,
minus the volume of a solid cylinder, 8-cm tall, with a diameter of 5 cm.
The volume of a cylinder is the area of the base, times the height.
The area of the cicular base is times the square of the radius

Putting it all together, for a cylinder,
, where
= radius of the cylinder = , and
= height of the cylinder

The volume of the outside cylinder (in ) is .
The volume of the inside cylinder (in ) is .
The volume of the piece of pipe (in ) is
= about .
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