Volume - Hollow Cylinder

[Guest]

A hollow aluminum tube is 88 ft. long and 1.25 in. in diameter. Determine volume.

Volume of hollow cylinder: pi * h * (R^2 - r^2).

My attempt:

3.1416 * 88 * 0.625 * 0.625 * 0.3125 * 0.3125 = 10.5461 = 10.55 cu. ft.


Not sure if my calculations are correct.

[HallsofIvy]

It would help if you told us what the problem really is!

what you wrote: "A hollow aluminum tube is 88 ft. long and 1.25 in. in diameter. Determine volume" is meaningless! The volume if what? The volume of aluminum or the volume of the hollow? And what "diameter" do you mean? Is it the outer diameter of the tube or the inner volume of the hollow part?

Your formula appears to be for the volume of the aluminum. No, your calculations are not correct. The formula involves R squared minus r squared but you have no subtraction, only multiplications. I can see that "0.625" is half of 1.25, but where did you get "0.3125"? That's half if 0.625 but why? Is 1.25 the outer diameter and the inner diameter is half of that? You did not say that.

It is impossible to tell whether your final answer is correct or not because you haven't given all the information. The formula you give requires both "R" and "r", the outer and inner radii but you given only one diameter. My guess is that 1.25 is the outer diameter and 2*0.3125=

[Guest]

Only outside diameter given; inside not given.

Trying to determine volume of aluminum.

.3125 is error.

Thanks.

[Guest]

Please reply. Thanks.

[HallsofIvy]

If this is a hollow cylinder then you must know the inner diameter to solve the problem.

[Guest]

Ok, Thanks.