A horizontal flag is shown below. The radius of the outer semicircle is $4$, while that of the inner semicircle is $3$.

1. Imagine rotating the flag about its pole and describe the resulting three-dimensional figure. Draw a picture of this figure on your paper.

   Hint (a):

   Imagine a hollow rubber ball. The rubber is $1$-inch thick and the radius is $3$ inches.

2. Find the volume of the rotated flag.

   Hint (b):

   Volume = big sphere − small sphere

   Answer (b):

   $\frac{4}{3}\pi(4)^3-\frac{4}{3}\pi(3)^3=\frac{148}{3}\pi \text{ un}^{3}$