The following histogram shows the number of miles Bryan ran each day in preparation for a half marathon. Histogram of miles ran, with number of miles run each day on the x-axis and number of days on the y-axis. There are five bins. They go from 1 to 3, 3 to 5, 5 to 7, 7 to 9, and 9 to 11. The heights of the bins from left to right are 8, 9, 4, 8, and 2. The bar with endpoints 7 and 9 has a height of 8. What does this mean?