How much material is required to make a pipe that is 300 cm long whose outer diameter is 8 cm with an inner diameter of 5 cm? Show or explain your work.

Step-by-step explanation:

If you had a solid cylinder, in order to find the amount of material that makes up that solid cylinder, you would find the volume using the radius of 4 (half of the diameter 8).  BUT we want to know the volume of the solid with the radius of 4 minus the solid that has a radius of 2.5 (half of the diameter 5).

 That's volume outer - volume inner.  To find the outer volume:

so

and

 and do the same for the inner volume:

and

Subtract the inner from the outer:

If you need your answer in decimal form, then the volume is

9189.16 cm³

x is variable or an unknown value to find

example:

2x = 5 which means x = 3

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