To calculate the volume of the cylindrical tanker filled with fuel, we can use the formula for the volume of a cylinder:
\[ V = \pi r^2 h \]
where:
- \( V \) is the volume,
- \( r \) is the radius of the cylinder,
- \( h \) is the height (or length) of the cylinder.
Given:
- radius \( r = 4 \) feet,
- height \( h = 50 \) feet.
Substituting the values into the formula:
\[ V = \pi (4^2)(50) \]
Calculating \( 4^2 \):
\[ 4^2 = 16 \]
Now substituting back into the volume formula:
\[ V = \pi (16)(50) \]
Calculating \( 16 \times 50 \):
\[ 16 \times 50 = 800 \]
Thus, the volume \( V \) becomes:
\[ V = 800\pi \]
So, the amount of fuel inside the tank is:
\[ \boxed{800\pi} \]