4. Find the volume of a frustum of a right pyramid whose lower base is a square with a side 5 in. and whose upper base is a square with a side 3 in., and whose altitude is 12 in. Round your answer to the nearest whole number.

Question

Mathematics

Denise

13 March, 22:31

4. Find the volume of a frustum of a right pyramid whose lower base is a square with a side 5 in. and whose upper base is a square with a side 3 in., and whose altitude is 12 in. Round your answer to the nearest whole number.

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Answers (1)

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Ariel Castro · Answer 1

The height of the complete pyramid which has a square base of length 5 can be found using similar triangles:-

3/5 = x / (x+12)

x = 0.6x + 7.3

0.4x = 7.2

x = 18

so height of full pyramid is 30 and volume of the frustum is

1/3 * 5^2 * 30 - 1/3 * 3^2 * 18

= 196 in^2