1. The problem statement, all variables and given/known data Determine the number of cubic yards of crushed rock necessary to make a roadbed with the cross-section shown below, if the road is to be 1/4 mile − long. Assume that the crown of the pavement is an arc of a parabola, with its vertex at the top center. Be careful with units. 3. The attempt at a solution First i found the volume of the lower part of the road bed and converted inches to feet. V= l*w*h =(1320ft)(20ft)(2/3ft) = 17600 ft^3 . 17600ft/3 = 5866.667 yds^3. Now I have to find the top part of the road which is where I'm stuck. I got an integral that was V= 1320ft * "integral from 0 to 4" (-x^2-x+4)dx which is V= 1320 ft * ((-x^3/3)-(x^2/4)+4x). Then I plugged in 4 and got -17600 ft^3. That can't be right though because when you add those volumes you get 0. What did I do wrong?