From the given history graph, the following are the runners that could run greater than 5.5 and less than 7.5 miles before they started to feel tired.
For runners that could run greater than 5.5 but less than 6.5 miles = 4 Runners
For runners that could run greater than 6.5 but less than 7.5 miles = 4 Runners
Therefore, the total number of runners that could run greater than 5.5 and less than 7.5 miles is:
Therefore, 8 runners could run greater than 5.5 and less than 7.5 miles.