1. Introduction to Graphing
Section 3.1
Introduction to Graphing

2. The Rectangular Coordinate System
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The Rectangular Coordinate System
One common way to graph data is to use the rectangular coordinate system, or xy-plane. In the xy-plane the horizontal axis is the x-axis, and the vertical axis is the y-axis. The axes intersect at the origin. The axes divide the xy-plane into four regions called quadrants, which are numbered I, II, III, and IV counterclockwise

3. Example
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Plot the following ordered pairs on the same xy-plane. State the quadrant in which each point is located, if possible. a. (4, 3) b. (3, 4) c. (1, 0) Solution a. (4, 3) Move 4 units to the right of the origin and 3 units up. b. (3, 4) Move 3 units to the left of the origin and 4 units down. c. (1, 0) Move 1 unit to the left of the origin.
Quadrant I
Quadrant III
Not in any quadrant

4. Example
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Frozen pizza makers have improved their pizzas to taste more like homemade. Use the graph to estimate frozen pizza sales in 1994 and Solution a. To estimate sales in 1994, locate 1994 on the x-axis. Then move upward to the data point and approximate its y-coordinate. about $2.1 billion in sales

5. Example (cont)
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Frozen pizza makers have improved their pizzas to taste more like homemade. Use the graph to estimate frozen pizza sales in 1994 and Solution b. To estimate sales in 2000, locate 2000 on the x-axis. Then move upward to the data point and approximate its y-coordinate. about $3.0 billion in sales

6. Scatterplots and Line Graphs
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Scatterplots and Line Graphs
If distinct points are plotted in the xy-plane, then the resulting graph is called a scatterplot.

7. Example
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Make a scatterplot of the data in the following table, which lists the price of a first-class postage stamp for selected years.
Year
1980
1990
2000
2010
Price (cents) 15 25 33 44

8. Page 163
Line Graphs
Sometimes it is helpful to connect consecutive data points in a scatterplot with line segments. This creates a line graph.

9. Example
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Use the data in the table to make a line graph. Solution Plot the points and then connect consecutive points with line segments. x 3 2 1 1 2 3 y 4

10. Example
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Use the figure to answer the questions. a. Which 10-year period had the greatest increase in energy consumption? 1970 to 1980 b. Estimate the energy consumption in About 310 million Btu

11. DONE

12. Objectives Tables and Graphs The Rectangular Coordinate System
Scatterplots and Line Graphs