how many cubic yards of earth must be removed in digging an artificial lake 180 in. deep, if the level bottom is a rectangle 180 ft by 20 ft and the top is a rectangle 220 ft by 25 ft?
I have my solution but I don't know why my answer is not in the choices.. Help pls?

Question

anonymous · Answer

i was trying to solve this but my answer is not in the choices :(

anonymous · Answer

here is my solution ..

tylerd · Answer

alright lets see, we have a trapezoidal pyramid looks like

tylerd · Answer

im getting a different volume in cubic ft

tylerd · Answer

(3600+5500+18000)(15/6)

tylerd · Answer

divide that by (3ft)^3 or 9, and we get that answer

tylerd · Answer

er 27

tylerd · Answer

i just used the equation on here http://www.had2know.com/academics/rectangular-trapezoid-trough-volume.html

anonymous · Answer

how did you get the mid-section ? @TylerD

anonymous · Answer

ok i get it