Hi John,

The volume is the area of the cross section times the length. The length you have is 125 feet so you need the area of the cross sections. The shape of the cross section is a trapezoid and an expression for its area can be found in our response to a previous question.

Since your dimensions are in feet this will give you the volume in cubic feet. If you want the volume in cubic yards you can determine it using Google or another search engine. Suppose you got the volume to be V cubic feet. Just type What is V cubic feet in in cubic yards? into the search engine. Since I'm a Mac user I would ask Siri. Hey Siri, what's V cubic feet in cubic yards?

Harley