"Published in Vacaville, California, USA"
A trench is 180 ft. long and 12 ft. deep, 7 ft. wide at the top and 4 ft. at the bottom. How many cubic yards of earth have been removed?
Solution:
To illustrate the problem, it is better to draw the figure as follows
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| Photo by Math Principles in Everyday Life |
The amount of earth removed is in the shape of a prism whose base is a trapezoid. The area of the base which is a trapezoid is
The amount of earth removed which is the volume of a trapezoid prism is
Therefore, the amount of earth removed in cubic yards is
