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A frustum of a regular square pyramid is formed by passing a plane 2 in. from the vertex of a square pyramid of altitude 10 in. and base edge 4 in. What is the volume of the frustum?
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The volume of the large pyramid is V = = {{in^3}}}.
The volume of the small pyramid is in times less than that,
because the similarity factor is 5. In other words, the volume of the small pyramid is v = {{in^3}}}.
Now the volume of the frustrum is the difference V - v.
You can calculate it yourself and represent it in any form you want/need.
For many problems on volume of pyramids see the lesson OVERVIEW of LESSONS on Volume of PYRAMIDS in this site.
For many problems on volume of other solids see the lesson LESSONS on Volume of 3D SOLID BODIES.