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Hole in a bead (Posted on 2004-08-21) Difficulty: 4 of 5
A round hole is drilled through the center of a spherical solid with a radius (r). The resulting cylindrical hole has height 4 cm.

a)What is the volume of the solid that remains?

b)What is unusual about the answer?

See The Solution Submitted by Pieater    
Rating: 3.0909 (11 votes)

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easy as pi | Comment 9 of 13 |
The volume of the sphere is 4/3 pi r^3.  The volume of the cylinder is pi(2^2)(2r) = 8pi(r).  So the solid that remains is 4/3 pi r^3 minus 8 pi (r).  The interesting thing is that 8 pi (r) is the second derivative of 4/3 pi r^3.
  Posted by willow cliffswallow on 2004-09-16 14:51:12
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