Final answer:
The median is generally the best measure to show if most people do not exercise long enough since it is less affected by extreme values and represents the 'typical' amount of time spent exercising by individuals.
Step-by-step explanation:
When analyzing the data provided by twelve people regarding the time spent exercising each day, a reporter aiming to show that most people do not exercise long enough might choose different statistical measures based on what they want to demonstrate. If the data is skewed by a few individuals who exercise a lot, the mean might be higher and not represent the majority's exercise habits accurately. In contrast, the median is the middle value of a data set when it is arranged in ascending order, which is less affected by extreme values and might better represent the exercise duration of a 'typical' individual if the data is skewed. The mode is the most frequently occurring value and could be used if there is a common amount of exercise time that most participants adhere to, but it does not necessarily reflect whether people are exercising enough.
For the reporter's purpose, the median would likely be the best choice to show that most people do not exercise long enough since it is resistant to extreme values and would provide a clearer picture of what a 'typical' person does. For instance, if many people do not exercise at all or very little, those values would be reflected more accurately in the median than the mean.