Controlled Variable: The controlled variable in this scenario is the running speed of the person.
In scientific experiments, a controlled variable is also known as a constant variable. This is a factor that is intentionally kept consistent or unchanged throughout the experiment. It is used to ensure that any observed effects or changes in the dependent variable are solely due to the manipulation of the independent variable, rather than being influenced by other factors.
In the context of the time it takes to run a mile, the controlled variable is the running speed of the person. By keeping the running speed constant while measuring the time taken to complete a mile, researchers accurately assess the impact of changes in speed on the dependent variable (time).
The full question is:
The time it takes to run a mile depends on the person's running speed. What is a controlled variable?