To calculate the volume of a sphere, you can use the formula:
\[ V = \frac{4}{3} \pi r^3 \]
where \( V \) is the volume and \( r \) is the radius of the sphere.
First, you'll need to find the radius. The radius is half of the diameter. Given that the diameter is 7 inches, the radius \( r \) will be:
\[ r = \frac{7}{2} = 3.5 \text{ inches} \]
Now, substitute the radius into the volume formula:
\[ V = \frac{4}{3} \pi (3.5)^3 \]
Calculating \( (3.5)^3 \):
\[ (3.5)^3 = 3.5 \times 3.5 \times 3.5 = 42.875 \]
Now, substitute this back into the volume formula:
\[ V = \frac{4}{3} \times 3.14 \times 42.875 \]
Multiplying \( \frac{4}{3} \) by \( 3.14 \):
\[ \frac{4}{3} \times 3.14 \approx 4.1867 \]
Now, multiply that by \( 42.875 \):
\[ V \approx 4.1867 \times 42.875 \approx 179.4 \]
Thus, the volume of the sphere is approximately:
\[ \boxed{179.4} \text{ cubic inches} \]