To find the volume of a cone, you can use the formula:
\[ V = \frac{1}{3} \pi r^2 h \]
Where:
- \( V \) is the volume,
- \( r \) is the radius of the base,
- \( h \) is the height of the cone.
From the problem:
- The diameter of the cone is 4 meters, so the radius \( r \) is \( \frac{4}{2} = 2 \) meters.
- The height \( h \) is 6 meters.
Now substituting the values into the formula:
\[ V = \frac{1}{3} \times 3.14 \times (2^2) \times 6 \]
Calculating the radius squared:
\[ 2^2 = 4 \]
So the formula now looks like:
\[ V = \frac{1}{3} \times 3.14 \times 4 \times 6 \]
Now calculate \( 4 \times 6 \):
\[ 4 \times 6 = 24 \]
Now, substituting back in:
\[ V = \frac{1}{3} \times 3.14 \times 24 \]
Calculating \( 3.14 \times 24 \):
\[ 3.14 \times 24 = 75.36 \]
Now, finding \( \frac{1}{3} \times 75.36 \):
\[ V = \frac{75.36}{3} = 25.12 \]
Therefore, the volume of sand needed to fill the mold is:
\[ \boxed{25.12} \text{ cubic meters} \]