1. The problem statement, all variables and given/known data Water drains out of an inverted conical tank at a rate proportional to the depth (y) of water in the tank. Write a diff EQ as a function of time. This tank's water level has dropped from 16 feet deep to 9 feet deep in one hour. How long will it take before the tank is empty. 2. Relevant equations V=1/3pir2y dV/dt=pi(r0/y0)2y2dy/dt 3. The attempt at a solution The solution to the first question is: dy/dt=-k(y0/r0)2(1/piy) I don't really know how to go about finding the time it will take to empty the tank. Please help!