On page 115 of your reading material there is a chart showing the distance covered after a specified number of seconds of walking this kind of chart can only be produced in this way if?

the data collected is consistent and accurate, reflecting the actual distances walked at regular intervals. Additionally, the walking speed must remain relatively constant throughout the measurement period to ensure the chart's reliability. Any variations in speed or inaccuracies in data could lead to misleading representations of distance covered over time.