Filling Cylindrical HolesDate: 05/18/99 at 13:30:44 From: Daymon Raue Subject: volume of cylinder Dear Dr. Math, I'm filling holes with cement. There are 42 holes they have a 9" diameter and are 4' deep. We want to figure out how much cement it will take in yards. If you please figure this out and tell me the answer, I would appreciate that. Daymon Raue Date: 05/18/99 at 16:07:40 From: Doctor Rob Subject: Re: volume of cylinder Thanks for writing to Ask Dr. Math! Each hole has a diameter of 1/4 yard, and so a radius of 1/8 yard, and a depth of 4/3 yard. The volume of a cylinder is Pi times the square of the radius, times the depth, so each hole has volume V = Pi*(1/8)^2*(4/3) = Pi/48 or, roughly, 3.1416/48 = 0.065450 cubic yards. Now multiply that by the total number of holes -- 42 -- to get between 2 and 3 cubic yards, and you're done! - Doctor Rob, The Math Forum http://mathforum.org/dr.math/ |
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