A balloon is being filled with air at a rate of 3 cubic meters per minute. Find the rate at which the radius is changing when the volume is 36 pi cubic meters.
same deal
surface area = (4/3) pi r^2
V = 4 pi r^3
so r = (36/4pi)^(1/3)
dV/dt = 3 = (4/3)pi r^2 (dr/dt)