The scale given is 9 centimeters = 1 meter. To find the scale factor as a ratio, we can express both measurements in the same unit.
Since there are 100 centimeters in a meter, we can also express 1 meter as 100 centimeters. Therefore, we can rewrite the scale as:
9 centimeters = 100 centimeters.
Now, we can express this as a ratio:
\[ \text{Scale Factor} = \frac{9 \text{ cm}}{100 \text{ cm}}. \]
To simplify this, we can write:
\[ \frac{9}{100}. \]
This is already in the simplest form, so we can express the scale factor as a ratio:
\[ 9 : 100. \]
Thus, the scale factor used in the drawing is 9:100.