Question

Is the time it takes you to run a 100 meter race a function of the speed you run

Answer 1

Answer: Yes, the time it takes to run a 100 meter race is a function of the speed you run.

In a function, there is an input and only one corresponding output. In the case of a race time, it depends on your speed. 

A person with a slower speed will have a longer race time.
A person with a higher speed will have a shorter race time.