5. A downward-sloping straight line exhibits a direct relationship between two variables.
6. If two variables are inversely related, then they change in the same direction.
7. Two variables that are inversely related tend to move in opposite directions.
8. The slope of a line is calculated as the ratio of the “rise” over the “run”.
9. A horizontal line has an infinite slope.
10. A downward-sloping line has a negative slope.
11. A straight line or curve can shift when a factor not included on the vertical axis or horizontal axis
changes.
12. A graph can be used to illustrate the relationship between the price of compact discs and the quantity
of compact discs demanded. If there is evidence that buyers’ income also influences the demand for
compact discs, then a movement along the curve can be caused by a change in the price of compact
discs.