# Solved Problem 09 | Rectangular Parallelepiped

**Problem 9**

A solid concrete porch consists of 3 steps and a landing. The steps have a tread of 11 in., a rise of 7 in., and a length of 7 ft.; the landing is 6 ft. by 7 ft. How much material was used in its construction?

**Solution 9**

$V = \dfrac{28}{12}(6)(7) + \dfrac{21}{12} \left( \dfrac{11}{12} \right)(7) + \dfrac{14}{12} \left( \dfrac{11}{12} \right)(7) + \dfrac{7}{12}\left( \dfrac{11}{12} \right)(7)$

$V = 120.46 \, \text{ ft}^3$ *answer*

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