To find the width of the right rectangular prism, we can use the formula for the volume \( V \) of a rectangular prism:
\[ V = \text{length} \times \text{width} \times \text{height} \]
We are given:
- Volume \( V = 1000 \)
- Height \( h = 10 \)
- Length \( l = 20 \)
We can rearrange the formula to solve for width \( w \):
\[ w = \frac{V}{l \times h} \]
Now, substituting in the known values:
\[ w = \frac{1000}{20 \times 10} \]
Calculating the denominator:
\[ 20 \times 10 = 200 \]
Now, calculate the width:
\[ w = \frac{1000}{200} = 5 \]
So, the width of the rectangular prism is \( \boxed{5} \).