Presentation on theme: "Introduction to Graphing"— Presentation transcript:
1Introduction to Graphing Section 3.1Introduction to Graphing
2The Rectangular Coordinate System Page 160The Rectangular Coordinate SystemOne 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
3ExamplePage 161Plot 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 IQuadrant IIINot in any quadrant
4ExamplePage 161Frozen 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
5Example (cont)Page 161Frozen 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
6Scatterplots and Line Graphs Page 162Scatterplots and Line GraphsIf distinct points are plotted in the xy-plane, then the resulting graph is called a scatterplot.
7ExamplePage 162Make a scatterplot of the data in the following table, which lists the price of a first-class postage stamp for selected years.Year1980199020002010Price (cents)15253344
8Page 163Line GraphsSometimes it is helpful to connect consecutive data points in a scatterplot with line segments. This creates a line graph.
9ExamplePage 163Use the data in the table to make a line graph. Solution Plot the points and then connect consecutive points with line segments.x321123y4
10ExamplePage 164Use 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