To find the volume of a rectangular pyramid, you can use the formula:
\[ V = \frac{1}{3} \times B \times h \]
where:
- \( V \) is the volume,
- \( B \) is the area of the base,
- \( h \) is the height (altitude).
For a rectangular base, the area \( B \) can be calculated as:
\[ B = \text{length} \times \text{width} \]
In this case, the length is 30 cm and the width is 20 cm, so:
\[ B = 30 , \text{cm} \times 20 , \text{cm} = 600 , \text{cm}^2 \]
Now, using the height \( h = 49 , \text{cm} \), we can substitute the values into the volume formula:
\[ V = \frac{1}{3} \times 600 , \text{cm}^2 \times 49 , \text{cm} \]
Calculating that:
\[ V = \frac{1}{3} \times 600 \times 49 \]
\[ V = 200 \times 49 = 9800 , \text{cm}^3 \]
Thus, the volume of the rectangular pyramid is:
\[ \boxed{9800 , \text{cm}^3} \]