There exists a wall that is over 13,000 miles long. The length built during a particular dynasty is 5,500 miles. The cross section of the wall is a trapezoid 28 feet high, 22 feet wide at the bottom, and 16 feet wide at the top. How many cubic yards of material make up the (5,500 miles) portion of the wall?

I realize that I use the formula to solve area of the trapezoid but I do not know what comes next?

2 answers

the trapezoid is the base of the solid. As with all prisms, volume is base*height. (in this case, since the prism is lying on its side, it's the length of the wall)

v = (22+16)/2 * 28 * (1/5280)^2 * 5500 = 655/6336 mi^3
Thank You that help me understand the problem! And where does the 5280 come from? I do not understand that part?