Final answer:
The slope of Song 2 between minute 6 and minute 7 is zero because there is no change in the number of downloads, and thus, the graph would show a horizontal line during that interval.
Step-by-step explanation:
The slope of a graph represents the rate of change of a line and is calculated as the change in the vertical direction (rise) divided by the change in the horizontal direction (run). For Song 2 between minute 6 and minute 7, if the line is horizontal, then there is no change in the vertical direction (the number of downloads does not increase or decrease). In this case, the slope would be zero because the rise (change in downloads) over run (change in time) equals zero.
To differentiate between different slopes, remember: a positive slope means the line is going upward as it moves from left to right, a negative slope indicates the line is going downward, and a zero slope is observed when the line is perfectly horizontal, indicating no change in the value being measured as the independent variable changes.