Answer:
11 km/hr.
Explanation:
Given information:
Simulated speed = 20/km/h
Time = 15 mins = 1/4 hr = 0.25 hr
Distance Covered as per simulated speed =

Position of Julian according to the app =
.
Actual distance covered by the bike is

Formula for speed:



Therefore, the average speed of Julian is 11 km/hr.