pumping out a liquid - work

A tank in the shape of an inverted right circular cone has height http://webwork2.asu.edu/webwork2_fil...fc95b6a081.png meters and radius http://webwork2.asu.edu/webwork2_fil...0ef0978d41.png meters. It is filled with http://webwork2.asu.edu/webwork2_fil...47b840b231.png meters of hot chocolate.

Find the work required to empty the tank by pumping the hot chocolate over the top of the tank. Note: the density of hot chocolate is http://webwork2.asu.edu/webwork2_fil...61b7b03a91.png

Can anyone see where i went wrong?

Thanks for any help :)