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Section 2.4

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Representing Data Standard I&E: 1a Mastering Concepts: 50(69-71) Terms: 43

Homework:Cornell Notes: 2.4Section Assessment: 45(45-48) Mastering Problems: 50 (86-87) 6 stamps

Section 2-4Section 2.4 Representing Data

• Create graphics to reveal patterns in data.

independent variable: the variable that is changed during an experiment

graph

• Interpret graphs.

Graphs visually depict data, making it easier to see patterns and trends.

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69. Which type of graph would you choose to depict data on how many households heat with gas, oil, or electricity? Explain. (2.4)

A bar graph could be used with the method of heating on the x-axis and the number of households on the y-axis.

If the data include all the households for a region, relative numbers could be converted to a percentage and expressed as a circle graph.

Mastering Concepts: 50(69-71)

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70. Which type of graph would you choose to depict changes in gasoline consumption over a period of ten years? Explain. (2.4)

line or bar graph because they can show how consumption varies with time

71. How can you find the slope of a line graph? (2.4)

Choose two points on the line. Divide the difference in the y values by the difference in the x values.

Mastering Concepts: 50(69-71)

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Section 2.4 Assessment page 45

45. Explain why graphing can be an important tool for analyzing data.

It provides visual information about relationships between variables, relative amounts, or parts of a whole.

46. What type of data can be displayed on a circle graph? On a bar graph?

parts of a whole; how a quantity varies with a factor

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Section 2.4 Assessment page 45

47. If a linear graph has a negative slope, what can you say about the dependent variable?

It decreases in value as the independent variable increases.

48. When can the slope of a graph represent density?

when mass is the y value and volume is the x value

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Problem-solving LabStopping distance (m)

Speed (m/s)

18 1132 1649 2068 2592 29

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How does speed affect stopping distance?

100

80

60

40

20

0 0 10 20 30

Speed(m/s)

Dis

tanc

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Section 2-4Graphing

• A graph is a visual display of data that makes trends easier to see than in a table.

Section 2-4Graphing (cont.)

• A circle graph, or pie chart, has wedges that visually represent percentages of a fixed whole.

Section 2-4Graphing (cont.)

• Bar graphs are often used to show how a quantity varies across categories.

Section 2-4Graphing (cont.)

• On line graphs, independent variables are plotted on the x-axis and dependent variables are plotted on the y-axis.

Section 2-4Graphing (cont.)

• If a line through the points is straight, the relationship is linear and can be analyzed further by examining the slope.

Section 2-4Interpreting Graphs

• Interpolation is reading and estimating values falling between points on the graph.

• Extrapolation is estimating values outside the points by extending the line.

Section 2-4Interpreting Graphs (cont.)

• This graph shows important ozone measurements and helps the viewer visualize a trend from two different time periods.

End of Section 2-4