Final answer:
A positive slope indicates that as the independent variable increases, the dependent variable also increases. A negative slope indicates that as the independent variable increases, the dependent variable decreases. A zero slope means that there is no change in the dependent variable for a unit increase in the independent variable.
Step-by-step explanation:
The appearance of a positive slope differs from a negative slope and zero slope in the direction and magnitude of the line. A positive slope means that as the independent variable increases, the dependent variable also increases. For example, in the context of the third exam and final exam scores, a positive slope indicates that as the third exam score increases, the final exam score also increases. A negative slope, on the other hand, indicates that as the independent variable increases, the dependent variable decreases. Finally, a zero slope means that there is no change in the dependent variable for a unit increase in the independent variable.