Final answer:
The number of days Melanie ran would correlate with the number of marks on the line plot, with each mark representing a day of running.
Step-by-step explanation:
Without the specific line plot of Melanie's training mileage, we can't provide an exact numerical answer. However, I can guide you through how you would generally solve such a problem.
When analyzing a line plot, each mark corresponds to an instance of that data point being recorded. To determine how many days Melanie ran, you would count the number of marks on the line plot. Suppose there are marks above the numbers 2, 3, 4, 4, and 5 miles. That would indicate that she ran on five separate days, with two days running 4 miles each. Therefore, you would simply count each distinct mark as one day of running.