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Home > CCG > Chapter 11 > Lesson 11.2.2 > Problem 11-100

11-100.

The solid at right is an example of a truncated pyramid. It is formed by slicing and removing the top of a pyramid so that the slice is parallel to the base of the pyramid. If the original height of the square-based pyramid at right was cm, find the volume of this truncated pyramid. (Hint: You may find your results from problem 11‑86 useful.)  

A square pyramid, with the bottom portion solid and shaded, and the top portion, outlined with dashed lines. Bottom base sides, labeled, 9 cm. Square at base of dashed pyramid top, has side labeled 3 cm.

Find the volume of the large pyramid.

The side of the small pyramid is  the side of the large pyramid, because  is  of 

So, the lsf is .

Find the volume of the small pyramid.

Subtract the volume of the smaller pyramid from the volume of the larger pyramid.