1. SDAP1.2 Represent two numerical variables on a scatterplot and informally describe how the data points are distributed and any apparent relationship that exists between the two variables (e.g., between time spent on homework and grade level).
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2. A scatter plot is a graph with points plotted to show a possible relationship between two sets of data.

3. Additional Example 1: Making a Scatter Plot of a Data Set
Use the given data to make a scatter plot of the weight and height of each member of a basketball team.
Use the table to make ordered pairs for the scatter plot.
The points on the scatter plot are (71, 170), (68, 160), (70, 175), (73, 180), and (74, 190).

4. Check It Out! Example 1 Weight Height
Use the given data to make a scatter plot of the weight and height of each member of a soccer team.
Use the table to make ordered pairs for the scatter plot.
200
190
180
170
160
150
140
130
120
Height (in)
Weight (lbs) 63
125 67
156 69
175
Weight 68
135 62
120
The points on the scatter plot are (63, 125), (67, 156), (69, 175), (68, 135), and (62, 120).
Height

5. A correlation describes a relationship between two data sets
A correlation describes a relationship between two data sets. The correlation can help you analyze trends and make predictions. There are three types of correlations between data.

6. Additional Example 2: Determining Relationships Between Two Sets of Data
Write positive correlation, negative correlation, or no correlation to describe each relationship. Explain.
The graph shows that as area increases, population increases.
The graph shows a positive correlation between the data sets.

7. Check It Out! Example 2
Write positive correlation, negative correlation, or no correlation to describe each relationship. Explain.
The graph shows that as the year increases, number of tornados increases.
The graph shows a positive correlation between the data sets.

8. A line of best fit, or trend line, is a straight line that approximates the relationship between the data on a scatter plot. You can also use a line of best fit when making predictions based on data.

9. Additional Example 3: Using a Scatter plot to Make Predictions
Use the data to predict how much a worker will earn in tips in 10 hours.
Draw a line that has about the same number of points above and below it. Your line may or may not go through the data points.
Find the point on the line whose x-value is 10. The corresponding y-value is 24.
According to the graph, a worker will earn approximately $24 in tips in 10 hours.

10. Circuit Board Assemblies
Check It Out! Example 3
Use the data to predict how many circuit boards a worker will assemble in 10 hours.
Hours Worked 4 8 6 9 11
Circuit Board Assemblies 2 7 5 12
Draw a line that has about the same number of points above and below it. Your line may or may not go through the data points.
Circuit Board Assemblies
Find the point on the line whose x-value is 10. The corresponding y-value is 10.
Hours
According to the graph, a worker will assemble approximately 10 circuit boards in 10 hours.