Answer:
Julia rides faster than Katie by a factor of 4.6 miles per hour.
Explanation:
We are given the following information in the question:
Distance covered bu Julia = 20 miles
Time taken by Julia to cover this distance = 1.2 hours
Distance covered bu Katie = 20 miles
Time taken by Katie to cover this distance = 1.6 hours
Formula:

Julia's Speed =

Katie's Speed =

Difference between Julie's and Katie's speed = 16.66 - 12.5 = 4.6 miles per hour
Julia rides faster than Katie by a factor of 4.6 miles per hour.