# A metal pipe has outer diameter 5mm and 3mm thick metal. Calculate the volume used to make this metal pipe if the length of the pipe is 18cm long.

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### 1 Answer

To calculate, basically find the outer volume minus the inner volume:

`V=pir^2h` becomes `V=pi h ((r_(1))^2- (r_(2))^2)`

First convert the cm into mm. Thus the length = 180mm.The thickness of the pipe is 3mm so the inner diameter (d) = 2mm

If `d_1 = 5 therefore r_1=2.5` and `d_2=2therefore r_2=1`

`V=pi times 180( 2.5^2-1^2)`

`therefore V=2968.81 mm^3`

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