To find the width of the right rectangular prism, we can use the formula for the volume of a rectangular prism:
\[ \text{Volume} = \text{length} \times \text{width} \times \text{height} \]
We know the volume is 1,000, the height is 10, and the length is 20. Plugging in these values, we have:
\[ 1000 = 20 \times \text{width} \times 10 \]
Simplifying the equation, we calculate:
\[ 1000 = 200 \times \text{width} \]
Now, to find the width, we can divide both sides by 200:
\[ \text{width} = \frac{1000}{200} = 5 \]
Therefore, the width is 5.