SOLUTION: How many cubic yards of earth must be used to make a railroad embankment 500 ft. long if a cross section of the embankment is an isosceles trapezoid whose bases are 20 ft. and 45 f

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Question 1018065: How many cubic yards of earth must be used to make a railroad embankment 500 ft. long if a cross section of the embankment is an isosceles trapezoid whose bases are 20 ft. and 45 ft. and whose legs are each 18 ft. ?
Answer by FrankM(1040) About Me  (Show Source):
You can put this solution on YOUR website!

This is what it looks like. Since the top base is 25 less than the bottom, the 'extra' is 12.5 on each side.
The height is
sqrt%28%2818%5E2%29-%2812.5%29%5E2%29%29%29=(12.95)
Then just multiply by 65/2
420.93
But this is cubic ft, so divide by 27, to get 15.59 cubic yards.