To determine the scale factor of Jen's drawing, we need to compare the real-life length of the goat pen to its length in the drawing.
- Real-life length of the goat pen: 8 meters
- Length of the goat pen in the drawing: 2 centimeters
First, we need to convert the real-life measurement to the same unit as the drawing. Since the drawing's length is in centimeters, we will convert 8 meters to centimeters:
\[ 8 \text{ meters} = 8 \times 100 \text{ centimeters} = 800 \text{ centimeters} \]
Next, we set up the ratio of the real-life measurement to the drawing measurement:
\[ \text{Scale Factor} = \frac{\text{Real Life Length}}{\text{Drawing Length}} = \frac{800 \text{ cm}}{2 \text{ cm}} \]
Now, we simplify the ratio:
\[ \frac{800}{2} = 400 \]
Thus, the scale factor is \(400:1\).
So the final answer as a ratio is:
\[ \boxed{400:1} \]