1. Review of Essential Math and Graphing Skills
Econ 201 Summer
Review of Essential
Math and Graphing Skills

2. Using Graphs and Formulas
Appendix
Using Graphs and Formulas
A graph is like a street map—it is a simplified version of reality.

3. Appendix
Graphs of One Variable
FIGURE 1A-1
Bar Graphs and Pie Charts

4. Appendix
Graphs of One Variable
FIGURE 1A-2
Time-Series Graphs

5. Appendix Graphs of Two Variables FIGURE 1A-3
Plotting Price and Quantity Points in a Graph

6. Appendix Graphs of Two Variables Slopes of Lines FIGURE 1A-4
Calculating the Slope of a Line

7. Appendix Graphs of Two Variables
Taking into Account More Than Two Variables on a Graph
FIGURE 1A-5
Showing Three Variables on a Graph

8. Appendix Graphs of Two Variables Positive and Negative Relationships
FIGURE 1A-6
Graphing the Positive Relationship between Income and Consumption

9. Appendix Graphs of Two Variables Determining Cause and Effect
FIGURE 1A-7
Determining Cause and Effect

10. Appendix Graphs of Two Variables
Are Graphs of Economic Relationships Always Straight Lines?
The graphs of relationships between two economic variables that we have drawn so far have been straight lines.
The relationship between two variables is linear when it can be represented by a straight line.
Few economic relationships are actually linear.

11. Appendix Graphs of Two Variables Slopes of Nonlinear Curves
FIGURE 1A-8
The Slope of a Nonlinear Curve

12. Appendix Formulas Formula for a Percentage Change
One important formula is the percentage change.
The percentage change is the change in some economic variable, usually from one period to the next, expressed as a percentage.

13. Appendix Formulas Formulas for the Areas of a Rectangle and a Triangle
FIGURE 1A-9
Showing a Firm’s Total Revenue on a Graph

14. Appendix Formulas Formulas for the Areas of a Rectangle and a Triangle
FIGURE 1A-10
The Area of a Triangle

15. Appendix Formulas Summary of Using Formulas
Whenever you must use a formula, you should follow these steps:
1 Make sure you understand the economic concept that the formula represents.
2 Make sure you are using the correct formula for the problem you are solving.
3 Make sure that the number you calculate using the formula is economically reasonable. For example, if you are using a formula to calculate a firm’s revenue and your answer is a negative number, you know you made a mistake somewhere.