Answer:
The magnitude of his average velocity for the 200.0 m is zero.
Step-by-step explanation:
Given that,
Distance = 100.0 m
Time = 9.86 s
Now, back to his starting point
Time = 90.9 s
Average velocity :
Average velocity is equal to the total displacement divided by the total time.
In mathematical form,

Where, D = Displacement
t = time
He started at the Start line, and ended at the Start Line.. his Net displacement will be Zero so the average velocity will be
Using formula of average velocity,


Hence, The magnitude of his average velocity for the 200.0 m is zero.