Warm Up

1. The constant in the _____________________ form is the

slope of the line.

2. The equation of a line is . What is the slope of the line?

3. Write the equation in slope intercept form.

4. Write an equation in slope intercept form for a line with a

slope of and a y-intercept of .

Lesson 71: Scatter PlotsPROBABILITY AND STATISTICS

Scatter Plots and Lines of Best Fit

Scatter plot: a graph that relates two sets of data with plotted ordered pairs

Trend line: a line on a scatter plot that shows the relationship between two sets of data

Correlation: a measure of the strength and direction of the association between data sets or variables The closer the points are clustered together, the stronger the

correlation

Positive correlation: occurs when data values for both variables increase

Negative correlation: occurs when data values for one variable increase while data values for the other variable decrease

Example

Use the data in the table to make a scatter plot, draw a trend line, and find an equation for the trend line.

X 1 2 3 4 5 6

Y 4 10 12 18 23 29

Your Turn

Use the data in the table to make a scatter plot, draw a trend line, and find an equation for the trend line.

X 1 2 3 4 5 6

Y 14 27 43 53 70 85

Example

a. b.

c. height and shoe size

d. Date of birth and shoe size0 1 2 3 4 5 6 7 8

0

1

2

3

4

5

6

7

State whether there is a positive correlation, a negative correlation, or no correlation between the data values.

X 10 9 8 7 6 5 4 3 2

Y 60 63 72 75 77 81 83 89 92

Your Turn

a. b. Outdoor temperature and the number of sweaters sold

c.

d. Hair color and height0 1 2 3 4 5 6 7 80

1

2

3

4

5

6

7

8

9

State whether there is a positive correlation, a negative correlation, or no correlation between the data values.

X 2 5 6 8 9 11 13 16 20

Y 10 12 13 15 17 20 21 24 26

Example

Match each situation with the scatter plot that models it best.

a. Number of trucks on the road and number of days in a month

b. Time spent driving and distance traveled

c. Number of months you own a car and the value of the car

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50123456789

0 1 2 3 4 5 6 7 80

1

2

3

4

5

6

7

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7

8

Graph 1 Graph 2 Graph 3

Your Turn

Match each situation with the scatter plot that models it best.

a. Time spent exercising and calories burned

b. Number of dishes washed and ounces of detergent in a bottle

c. Population of a country and number of states in the country

0 1 2 3 4 5 6 7 8 90

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7

8

Graph 1 Graph 2 Graph 3

Homework Questions

Homework Questions

Correcting Homework

Be kind.

If the paper in front of you has no work shown, return it to its owner.

If the paper in front of you is not in pencil or black ink, return it to its owner.

If the paper in front of you is not complete, return it to its owner.

Remember you are filling out the score sheet for the person that you are correcting.

Be sure to write “C.B. ____________” with your name on the paper you graded and on the score sheet.

Homework

1st and 2nd hour: Lesson 71 Practice A-B, D-L, #1-3, 6-9, 11-13, 18-21, 24-26, 29

3rd hour: Lesson 71 Practice A-B, D-L, #1, 11-13