To determine who ran a greater distance, it is necessary to add the time spent running each day to the chart. This additional information is crucial because:
1. Total Distance Alone is Not Sufficient: Knowing just the distances run by Nancy and Hiyang does not provide a full picture of their training activities. For example, if one runner covers the distance in a significantly shorter amount of time, that runner is likely running at a higher speed and possibly has better endurance.
2. Comparing Endurance and Speed: By having the time data, we can calculate their average speed (distance divided by time) for each day. This allows us to compare not only their total distances run but also their overall speed and endurance during their training sessions.
3. Finding Patterns and Trends: With both distance and time, we can identify patterns in their training, such as consistent improvements in speed or distance, highlighting who is training more effectively.
Given the choices:
- Time spent running each day: This is the correct information to be added.
- The reference point used each day: This information is not relevant to determining distance covered.
- The units used to measure distance each day: Assuming units are consistent for both runners (which is usually safe unless otherwise specified), this is not the crucial information needed here.
- The location used by the runners each day: While the location might give context to conditions they ran in, it does not directly help in determining who ran a greater distance.
Therefore, the crucial information needed to make this determination is the time spent running each day.
Thus, the correct answer is:
- the time spent running each day
