The region in the first quadrant bounded by the graphs of $\displaystyle y=\frac{1}{8}x^3$ and $\displaystyle y=2x$ is revolved about the y-axis. Find the volume of the resulting solid.

So basically it is $\displaystyle \int \pi(R)^2 - \pi(r)^2$ where $\displaystyle R$ is the outer Radius and $\displaystyle r$ is the inner radius. Is this correct thus far? My question is how do I depict from the graph what the outer and inner radius is? And how do I determine the limits? If I can figure out these aspects I should be able to take the integral from there.