7.1. Line Graphs and Scatter Plots http://www.ck12.org
Lesson Summary
In this lesson you learned how to represent data by graphing three types of line graphs-a straight line of the form
y=mx+b, a broken-line graph and a double line graph. You also learned about scatter plots and the meaning of
correlation as it applies to a scatter plot. In addition, you saw the result of drawing a line of best fit on a scatter plot.
Points to Consider
- Is a double line graph the only representation used to compare two sets of data?
- Does the line of best fit have an equation that would model the data?
- Is there another representation that could be used instead of a broken line graph?
Review Questions
- On the following graph circle the independent and dependent variables. Write a sentence to describe how the
independent (input) variable is related to the dependent (output) variable in each graph.
a.- Ten people were interviewed for a job at the local grocery store. Mr. Neal and Mrs. Green awarded each of
the ten people, points as shown in the following table:
Mr.Neal 30 22 25 17 17 39 33 38 27 33
Mrs.Green 25 20 21 15 16 35 30 32 23 22Draw a scatter plot to represent the above data. (You may use technology to do this).- The following data represents the fuel consumption of cars with the same size engine, when driven at various
speeds.
Speed(km/h 48 99 64 128 112 88 120 106
Fuel Consumption(km/L) 7 14 9 18 16 13 17 15a. Plot the data values.
b. Draw in the line of best fit.
c. Estimate the fuel consumption of a car travelling at a speed of 72 km/h.
d. Estimate the speed of a car that has a fuel consumption of 12 km/L.- Answer the questions by using the following graph that represents the temperature in◦Ffor the first 20 days
in July.