To find the scale factor from circle X to circle Z based on their circumferences, we can use the following steps:
- The circumference of circle X is 12π.
- The circumference of circle Z is 6π.
The scale factor can be calculated by taking the ratio of the circumferences:
\[ \text{Scale Factor} = \frac{\text{Circumference of Circle X}}{\text{Circumference of Circle Z}} = \frac{12\pi}{6\pi} = \frac{12}{6} = 2 \]
This means that circle X is 2 times larger than circle Z, or conversely, the scale factor from circle X to circle Z is:
\[ \text{Scale Factor} = \frac{1}{2} \]
In terms of ratios, this can be expressed as a ratio of 2:1, indicating that for every 2 units in circle X, there is 1 unit in circle Z.
Therefore, the correct answer is:
2:1 ratio of 2 to 1.