Looking at the image, we can see that the radius of each layer is double the radius of the previous layer.
If the third layer has a radius of 8 inches, the next layer will have a radius of 16 inches.
Now, to calculate the volume, we can use the formula below:
[tex]\begin{gathered} V=\pi r^2h\\ \\ V=3.1416\cdot16^2\cdot4\\ \\ V=3217\text{ in^^b3} \end{gathered}[/tex]