It takes Julian 1\2 hour to walk 2 miles. He decides to start working in his spare time, but because he wants to make sure he has enough time to go a desired distance he created the data table. At which ratio does the constant of proportionality appear?

Based on the given information, we can observe that Julian takes 1/2 hour to walk 2 miles. This means that the ratio of time to distance is constant: 1/2 hour : 2 miles. The constant of proportionality appears in this ratio, as it represents the relationship between the two quantities.