6-7
Scatter Plots and
Equations of Lines
6-7
1. Plan
Objectives
1
2
To write an equation for a
trend line and use it to make
predictions
To write an equation for a
line of best fit and use it to
make predictions
Check Skills You’ll Need
• To write an equation for a
Use the data in each table to draw a scatter plot. 1–2. See back of book.
trend line and use it to
make predictions
1.
x
• To write the equation for a
line of best fit and use it to
make predictions
x
y
2
1
21
3
8
2
3
15
12
9
25
4
5
9
7
. . . And Why
2
3
1
2
To use a trend line to make a
prediction, as in Example 1
4
5
1
Writing an Equation for a Trend Line
In Chapter 1 you used scatter plots to determine how two sets of data are related.
You can now write an equation for a trend line.
More Math Background: p. 306D
1
See p. 306E for a list of the
resources that support this lesson.
Length and Wingspan
of Hawks
Type of
Hawk
WingLength span
(in.)
(in.)
Cooper’s
21
36
Crane
21
41
Gray
18
38
Harris’s
24
46
Roadside
16
31
PowerPoint
Bell Ringer Practice
Check Skills You’ll Need
For intervention, direct students to:
Mean, Median, Mode, and Range
Lesson 1-6: Example 4
Extra Skills and Word
Problem Practice, Ch. 1
Broadwinged
19
39
Shorttailed
17
35
Swanson’s
19
46
SOURCE: Birds of North America
EXAMPLE
Trend Line
Birds Make a scatter plot of the data at the left. Draw a trend line and write its
equation. Use the equation to predict the wingspan of a hawk that is 28 in. long.
Step 1 Make a scatter plot
and draw a trend line.
Estimate two points on
the line.
Length and Wingspan
of Hawks
40
y - y1 = m(x - x1)
Use point-slope form.
y - 30 = 95 (x - 14)
Substitute 95 for m
and (14, 30) for (x1, y1).
y - 30 = 95(28 - 14) Substitute 28 for x.
y - 30 = 95(14)
Simplify within the
parentheses.
32
28
14
18 22 26
Length (in.)
y - 30 = 25.2
y = 55.2
Multiply.
Add 30 to each side.
The wingspan of a hawk 28 in. long is about 55 in.
Chapter 6 Linear Equations and Their Graphs
Special Needs
Below Level
L1
Some students may have difficulty plotting points
accurately on a grid. Have them work with a partner
to make sure each point is correctly positioned. Then
have them discuss the position of trend lines.
350
y 2y
9
2 30
m 5 x2 2 x1 5 39
19 2 14 5 5
2
1
Step 3 Predict the wingspan of a hawk that is
28 in. long.
36
Two points on the trend line
are (14, 30) and (19, 39).
350
Step 2 Write an equation of the trend line.
44
Wingspan (in.)
Lesson Planning and
Resources
y
Lesson 1-6
New Vocabulary • line of best fit • correlation coefficient
Math Background
Lines of best fit can be used to
determine whether slopes for two
sets of data are approximately
equal, indicating a similarity in
the relationships.
2.
1
Examples
Trend Line
Line of Best Fit
GO for Help
What You’ll Learn
learning style: visual
L2
To better understand a correlation coefficient, draw
and discuss scatter plots that show positive and
negative correlations with varying correlation
coefficients.
learning style: visual
Quick Check
1 Graph the data below and draw a trend line. Find an equation for the trend line.
Estimate the number of Calories in a fast-food that has 14g of fat. See back of book.
Calories and Fat in Selected Fast-Food Meals
Calories
Guided Instruction
6
7
10
19
20
27
36
276
260
220
388
430
550
633
Fat (g)
2. Teach
PowerPoint
Additional Examples
2
1
Writing an Equation for a Line of Best Fit
The trend line that shows the relationship between two sets of data most accurately
is called the line of best fit. A graphing calculator computes the equation of a
line of best fit using a method called linear regression.
The graphing calculator also gives you the correlation coefficient r, which tells
you how closely the equation models the data.
1
0
negative
correlation
no
correlation
Miles
1
EXAMPLE
positive
correlation
Line of Best Fit
Recreation Use a graphing calculator to find the
equation of the line of best fit for the data at the
right. What is the correlation coefficient to three
decimal places?
For: Correlation Activity
Use: Interactive Textbook, 6-7
Recreation
Expenditures
Year
1993
340
Step 1 Use the EDIT feature of the
screen on your graphing calculator.
Let 93 correspond to 1993 and 100 correspond
to 2000. Enter the data for years and then the
data for expenditures.
1994
369
1995
402
1996
430
1997
457
Step 2 Use the CALC feature in the
screen. Find the equation for the
line of best fit.
1998
489
1999
527
2000
574
slope
y-intercept
correlation
coefficient
SOURCE: Statistical
Abstract of the United
States. Go to
www.PHSchool.com
for a data update.
Web Code: atg-9041
PHSchool.com
For: Graphing calculator
procedures
Web Code: ate-2122
The equation for the line of best fit is y = 32.33x - 2671.67 for values of a and b
rounded to the nearest hundredth. The correlation coefficient is about 0.996.
Lesson 6-7 Scatter Plots and Equations of Lines
Advanced Learners
English Language Learners
L4
Make several scatter plots with different correlation
coefficients. Students match each scatter plot with its
corresponding correlation coefficient.
learning style: visual
2
EXAMPLE
10
14 18
22
46
71 78
107
Graphing
Calculator Hint
Point out that the equation of the
line of best fit will be in the form
y = ax + b or y = a + bx. The
coefficient of x is always the
slope and the constant is always
the y-intercept.
PowerPoint
Dollars
(billions)
LinReg
y axb
a 32.33333333
b 2671.666667
r2 .9929145373
r .9964509708
5
Time (min) 27
When the data points cluster around a line, there is a strong correlation between
the line and the data. So the nearer r is to 1 or -1, the more closely the data cluster
around the line of best fit. In later chapters, you will learn how to find non-linear
models which may better describe some data.
2
1 Make a scatter plot to
represent the data. Draw a
trend line and write an equation
for the trend line. Use the
equation to predict the time
needed to travel 32 miles on
a bicycle. See back of book.
Speed on a Bicycle Trip
351
ELL
For Exercises 6-11, help students understand the term
correlation by pointing out that it contains the word
relation. The correlation coefficient tells you how
closely related the equation and the data are.
learning style: verbal
Additional Examples
2 Use a graphing calculator to
find the equation of the line of
best fit for the data below. What
is the correlation coefficient?
U.S. Crime Rate
See back
(per 100,000 inhabitants)
of book.
Year
No. of Crimes
1995
5275.9
1996
5086.6
1997
4930.0
1998
4619.3
1999
4266.8
[Source: Crime in the United States,
1999, FBI, Uniform Crime Reports]
Resources
• Daily Notetaking Guide 6-7 L3
• Daily Notetaking Guide 6-7—
L1
Adapted Instruction
Closure
Ask: What is the difference
between a trend line and a line
of best fit? A trend line is an
approximation for a line of
best fit.
351
3. Practice
Quick Check
2 Find the equation of the line of best fit. Let 95 correspond to 1995 and 103
correspond to 2003. What is the correlation coefficient to three decimal places?
Assignment Guide
1 A B 1-6, 12-13, 15, 19
2000
7-11, 14, 16-18
20
21-23
24-35
EXERCISES
2002
2003
For more exercises, see Extra Skill and Word Problem Practice.
Practice and Problem Solving
Homework Quick Check
To check students’ understanding
of key skills and concepts, go over
Exercises 4, 10, 12, 15, 16.
A
Practice by Example
Example 1
Error Prevention!
GO for
Help
Exercise 1–5 Some students may
1–6. Trend lines
may vary. Samples
Find an equation of a reasonable trend line for each scatter plot. are given.
1.
2.
Animal Longevity
Cable TV
(page 350)
expect their trend lines to be
exactly like those of their
neighbors. Remind them that a
trend line is not precise. Thus,
their lines and equations may
differ slightly.
and Gestation
65
Gestation (days)
Test Prep
Mixed Review
2001
y ≠ 0.52x – 43.99; 0.990
60
55
50
3.
200
4.
NBA Players
Points per Game
400
10 20 30 40
Longevity (years)
y – 100 ≠ 15.71(x – 5)
’92 ’94 ’96 ’98
Year
y – 52.5 ≠ 2(x – 91)
Exercise 2 Ask students if these
data have a strong correlation
or a weak correlation.
600
0
’90
0
Memory Test
Response Speed (s)
C Challenge
Subscribers
(millions)
2 A B
22
20
18
80
60
40
20
16
0
GPS Guided Problem Solving
L4
L1
Adapted Practice
Practice
Name
Class
L3
Date
Practice 6-6
Scatter Plots and Equations of Lines
Decide whether the data in each scatter plot follow a linear pattern. If they
do, find the equation of a trend line.
1.
2.
y
7
6
20
15
10
5
21
4
3
x
O
3.
y
2
1O
4321
1
x
2 3 4 5 6
y
140
120
100
80
60
40
20 O x
7654321
1
1
Use a graphing calculator to find the equation of the line of best fit for the
following data. Find the value of the correlation coefficient r and determine
if there is a strong correlation between the data.
4.
x
y
x
y
1
7
1
6
2
5
2
15
4
8
15
50
3
-1
3
-5
8
3
18
14
4
3
4
1
13
10
21
28
5
-5
5
-2
19
13
24
36
5.
6.
x
y
1
7.
5
x
y
12
28
5.
Revenue
(billions of dollars)
L2
Reteaching
10.0
x
y
1
17
2
20
3
22
4
26
5
28
6
31
Year
U.S. Union
Membership
(millions)
1988
17.00
1989
16.96
1990
16.74
1991
16.57
1992
16.39
1993
9.
x
y
1
18
2
20
3
24
4
30
5
28
6
33
11.
U.S.
Year Unemployment
Rate (%)
1988
5.5
1989
5.3
1990
5.6
1991
6.8
1992
7.5
16.60
1993
6.9
1994
16.75
1994
6.1
1995
16.36
1995
5.6
1996
16.27
1996
5.4
1997
16.11
1997
4.9
1998
16.21
1998
4.5
Source: World Almanac
2000, p. 154.
352
10.
Source: World Almanac
2000, p. 145.
8.0
7.0
y – 7.5 ≠ 0.06(x – 280)
© Pearson Education, Inc. All rights reserved.
8.
Attendance and Revenue at U.S. Theme Parks
9.0
270 290 310 330
Attendance (millions)
Draw a scatter plot. Write the equation of the trend line.
352
70
5
72 74 76
y – 85 ≠ –15.25(x – 1)
Games Played
y – 16.4 ≠ 0.64(x – 69.9)
5. Graph the data in the table below for the attendance and revenue at theme
parks. Find an equation for a trend line of the data. See left.
0
L3
Enrichment
1
2
3
4
Study Time (min)
Year
1995 1996 1997 1998 1999 2000 2001 2002 2003
Attendance
(millions)
280
290
300
300
309
317
319
324
322
Revenue
(billions of
dollars)
7.4
7.9
8.4
8.7
9.1
9.6
9.6
9.9
10.3
SOURCE: International Association of Amusement Parks and Attractions.
Go to www.PHSchool.com for a data update. Web Code: atg-9041
Chapter 6 Linear Equations and Their Graphs
Average Annual Precipitation
(in.)
6.
58
6. Graph the data for the average July temperature and the annual precipitation of
the cities in the table below. Find an equation for the line of best fit of the data.
Estimate the average rainfall for a city with average July temperature of 758 F.
y
54
Precipitation and Temperature in Selected Eastern Cities
50
42
38
x
O 72 76 80 84
Average July
Temperature (ⴗF)
y ≠ 1.6x – 80; 40 in.
Exercise 7 Longitudes and
latitudes make up a coordinate
system used in designating the
location of places on the surface
of Earth. Latitude gives location
north or south of the equator. It is
expressed by angle measurements
ranging from 0° at the equator to
90° at the poles.
Average July
Temperature (ºF)
Average Annual
Precipitation (in.)
New York
76.4
42.82
Baltimore
76.8
41.84
Atlanta
78.6
48.61
Exercise 11 The r-value rounds to
Jacksonville
81.3
52.76
Washington, D.C.
78.9
39.00
1,000 since its value is
0.999808967.
Boston
73.5
43.81
Miami
82.5
57.55
City
46
Connection to Geography
SOURCE: Time Almanac
Graphing Calculator Use a graphing calculator to find the equation of the line
of best fit for the data. Find the value of the correlation coefficient r to three
decimal places.
Example 2
(page 351)
7.
Average Temperatures in Northern Latitudes
Latitude (º N)
Temp. (ºF)
0
10
20
30
40
50
60
70
80
79.2
80.1
77.5
68.7
57.4
42.4
30.0
12.7
1.0
y ≠ –1.06x ± 92.31.; –0.970
Retail Department Store Sales (billions of dollars)
8.
Year
1980
Sales
86
1985 1990
1994
1995 1996
1997 1998
126
217
231
261
166
245
279
SOURCE: Statistical Abstract of the United States.
Go to www.PHSchool.com for an update. Web Code: atg-9041
y ≠ 10.60x – 772.66; 0.991
9. Olympic 5000-Meter Men’s Gold Medal Speed Skating Times
Year
1980
1984
1988 1992
1994
1998 2002
Time
(seconds)
422
432
404
395
382
420
402
SOURCE: International Skating Union
y ≠ –1.63x ± 556.76; –0.725
10.
Average Male Lung Power
Respiration
(breaths/min)
Real-World
Heart Rate
(beats/min)
Connection
The 500-meter men’s speed
skating race has been an
Olympic event since 1924.
50
30
25
20
18
16
14
200
150
140
130
120
110
100
y ≠ 2.64x ± 70.51; 0.990
SOURCE: Encyclopeadia Britannica
Wind Chill Temperature for 15 mi/h Wind
11.
Air Temp. (ºF)
35
30
25
20
15
10
5
0
Wind-Chill Temp. (ºF)
16
9
2
5
11
18
25
31
y ≠ 1.35x – 31.42; 1.000
Lesson 6-7 Scatter Plots and Equations of Lines
353
353
Connection to Geometry
B
Exercise 12 The circumference of
a circle divided by its diameter
equals p.
pages 352–356
12a.
Apply Your Skills
12c. Answers may vary.
Sample: The slope
is the approximate
ratio of the
circumference to
the diameter.
Exercises
y
28
14
Population Growth
O
2
13a.
Female (millions)
144
6
10
x
y
1790
140
136
128
x
122 126 130 134 138
Male (millions)
b. Answers may vary.
Sample:
y ≠ 0.939x ± 13.8
d. Answers may vary.
Sample: No, the year is
too far in the future.
14a. Check students’ work.
b. 1
Today
More than 2 persons
per square mile
15. Answers may vary.
Sample: Pos. slope;
as temp. increases,
more students are
absent.
Stopping Distance (ft)
1 20a.
y
y≠
4.82x
–
29.65
132
66
O
Cylinder Tops
Diameter (cm)
16 32 x
Speed (mi/h)
16a. y ≠ 0.61x ± 35.31
b. Answers may vary.
Sample: No; small
set of data with
weak correlation
3
3
Circumference (cm) 9.3 9.5
5
6
8
16
18.8
25
8
9.5
10
10
12
25.6 29.5 31.5 30.9 39.5
a. Graph the data. See margin. b. Find the equation of a trend line.
y ≠ 3.25x – 1
c. What does the slope of the equation mean? See left.
d. Find the diameter of a cylinder with a circumference of 45 cm. about 14 cm
13a–b. See margin.
13. Population Use the data at the right.
Estimated Population of
the United States (thousands)
a. Graph the data for the male and female
populations of the United States.
Year
Male
Female
b. Find the equation of a trend line.
1991
122,956
129,197
c. Use your equation to predict the number
of females if the number of males were to
1992
124,424
130,606
increase to 150,000,000. 154,650,000
1993
125,788
131,995
d. Critical Thinking Would it be reasonable
to predict the population in 2025 from
these data? Explain. See margin.
1860
132
O
12. Geometry Students measured the diameters and circumferences of the tops of
GPS a variety of cylinders. Below is the data that they collected.
14. a. Open-Ended Make a table of data for
a linear function. Use a graphing calculator
to find the equation of the line of best fit.
b. What is the correlation coefficient for your
linear data? a–b. See margin.
15. Writing What kind of trend line do you think
data for the following comparison would be
likely to show? Explain. See left.
temperature and the number of students
absent from school
1994
127,049
133,278
1995
128,294
134,510
1996
129,504
135,724
1997
130,783
137,001
1998
132,030
138,218
1999
133,277
139,414
2000
138,054
143,368
SOURCE: U.S. Census Bureau. Go to
www.PHSchool.com for a data update.
Web Code: atg-9041
16. Graphing Calculator A school collected data on math and science grades of
nine randomly selected students.
Student
1
2
3
4
5
6
7
8
9
Math
76
89
84
79
94
71
79
91
84
Science
82
94
89
89
94
84
68
89
84
a. Use a graphing calculator to find the equation of the line of best fit for
the data. a–b. See left.
b. Critical Thinking Should the equation for the line of best fit be used to
predict grades? Explain.
17. Graphing Calculator Use a graphing calculator to find the equation of the line
of best fit for the data below. Predict sales of greeting cards in the year 2010.
Greeting Card Sales
Year
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
Sales
(billions)
$4.2
$4.6
$5.0
$5.3
SOURCE: Greeting Card Association
y ≠ 0.37x – 28.66; $12.04 billion
354
354
Chapter 6 Linear Equations and Their Graphs
$5.6
$5.9
$6.3
$6.8
$7.3
$7.5
GO
nline
Homework Help
Visit: PHSchool.com
Web Code: ate-0607
18. a. Data Collection Find two sets of data that you could display in a scatter
plot, such as the number of boys and girls in each class in your school, or the
population and the number of airports in some states. Then graph the data.
b. Find the equation of a trend line.
c. Use the equation to predict another value that could be on your scatter plot.
d. What is the correlation coefficient? a–d. Check students’ work.
4. Assess & Reteach
PowerPoint
Lesson Quiz
19. Another way you can find a line of best fit is the median-median method. The
graph below shows how this method works. The points in red indicate the
original data.
y
8
y
y
8 Line between
Median
points
first and last
6 median points
6
6
4
4
4
2
2
2
0
2
4
6
Divide the data into
three groups of equal
size.
x
8
0
2
4
6
Find and plot the
median points,
(x-median, y-median).
x
8
Line of
best fit
0
2
4
x
8
6
Challenge
20c. The speed is much
faster than those
speeds used to find
the equation of a
trend line.
Find the line parallel to the line
between the first and last
median points and 13 of the way
to the middle median point.
20. a. Make a scatter plot of the data below. Then find the equation of the line of
best fit. See margin.
Car Stopping Distances
Speed (mi/h)
10
15
20
25
30
35
40
45
Stopping Distances (ft)
27
44
63
85
109
136
164
196
71.1
80.8
86.8
93.3
99.0
[Source: U.S. Census Bureau, Current
Population Reports. From Statistical
Abstract of the United States, 2000]
a. Estimate two coordinates on the purple line in the graph at the right above.
Find the equation of the line of best fit. (2, 3) and (6, 6); y ≠ 0.75x ± 1.5
b. Graphing Calculator You can use a graphing calculator to find the line
of best fit with the median-median method. Below are the coordinates
of the points graphed in red. Use the EDIT feature of the
screen
on your graphing calculator. Use the Med-Med feature to find a line of
best fit. y ≠ 0.75x ± 1.21
(1, 2), (1, 3), (2, 3), (2, 4), (3, 2), (3, 3), (4, 3), (5, 1), (6, 6), (7, 9), (8, 8), (8, 7)
C
(millions)
1975
1980
1985
1990
1995
b. Use your equation to predict the stopping distance at 90 mi/h. 404 ft
c. Critical Thinking The actual stopping distance at 90 mi/h is close to 584 ft.
Why do you think this is not close to your prediction? See left.
1. Graph the data in a scatter
plot. Draw a trend line.
Household (millions)
8
Number of Households in the U.S.
Year Households
100
95
90
85
80
75
70
O
y
'75
'80
'85
'90 '95
'00
Year
2. Write an equation for the
trend line. y – 86.8 ≠
1.3(x – 85)
3. Predict the number of
households in the U.S. in 2005.
(Use 105 for x.) about 112.8
million households
4. Use a calculator to find the line
of best fit for the data.
y ≠ 1.366x – 29.91
5. What is the correlation
coefficient? 0.9943767027
Alternative Assessment
Test Prep
Multiple Choice
21. A horizontal line passes through (5, -2). Which other point does it also
pass through? B
A. (5, 2)
B. (-5, -2)
C. (-5, 2)
D. (5, 0)
22. Which of the following equations has a graph that contains the ordered
pairs (-3, 4) and (1, -4)? H
F. x + 2y = 8 G. 2x - y = 4
H. 2x + y = -2
J. x - 2y = -6
lesson quiz, PHSchool.com, Web Code: ata-0607
Lesson 6-7 Scatter Plots and Equations of Lines
Have students search for data
that would be suitable for a
scatter plot. Each student should
graph the data, find a trend line,
and then use a graphing
calculator to find the line of best
fit and the correlation coefficient.
355
355
Test Prep
Extended Response
Resources
For additional practice with a
variety of test item formats:
• Standardized Test Prep, p. 369
• Test-Taking Strategies, p. 364
• Test-Taking Strategies with
Transparencies
Alternative Method
23. The table right shows the number
of elderly in the United States
from 1960 through 2000.
a. Graph the data and draw a
trend line.
b. Write an equation for the
trend line you drew.
c. Predict the elderly population
in the United States in 2005.
Show your work.
a–c. See margin.
U.S. Elderly Population
more than one way to solve a
problem. For Exercise 22, you can
substitute both points into each
equation or use the two points to
find an equation.
Lesson 6-6
Lesson 4-4
30. x S 134
31. x R 5
32. x S –1
Checkpoint Quiz 2
Grab & Go
• Checkpoint Quiz 2
1960
16.560
1970
19.980
1980
25.550
1990
31.235
2000
34.709
Mixed Review
GO for
Help
Resources
Elderly
(millions)
SOURCE: Statistical Abstract of the United States.
Go to www.PHSchool.com for a data update.
Web Code: atg-9041
Exercise 22 Many times there is
Use this Checkpoint Quiz to check
students’ understanding of the
skills and concepts of Lessons 6-5
through 6-7.
Year
Write the equation for the line that is parallel to the given line and that passes
through the given point.
y – 4 ≠ –23 (x ± 1)
y ± 3 ≠ 5(x – 2)
24. y = 5x + 1; (2,-3)
25. y = -x - 9; (0, 5)
26. 2x + 3y = 9; (-1, 4)
y – 5 ≠ –x
1
27. y = -2x; (3, -4)
28. y = -2x + 3; (-2, -1) 29. y = 23x + 7; (-1, 2)
1
y ± 1 ≠ –2(x ± 2)
y – 2 ≠ 23 (x ± 1)
y ± 4 ≠ –2 (x – 3)
Solve each inequality. 30–32. See left
30. 1 + 5x + 1 . x + 9
31. 7x + 3 , 2x + 28
32. 4x + 4 . 2 + 2x
33. 4x + 3 # 2x - 7
x K –5
34. -x + 5 , 3x - 1
x S 32
35. 2x . 7x - 3 - 4x
xR3
Checkpoint Quiz 2
Lessons 6-5 through 6-7
1–3. See left.
Write an equation for the line through the given point that has the given slope.
1. (3, 4); m = 2 14
1. y – 4 ≠ –14 (x – 3)
2. y ± 3 ≠ 18x
3. y ≠ –5
23. [4] a.
Elderly (millions)
pages 352–356
6. 3x + 2y = 1; (-2, 6)
y – 6 ≠ –32 (x ± 2)
Write an equation of the line that is perpendicular to the given line and that passes
through the given point.
Exercises
8. y = 23 x + 6; (-6, 2)
y – 2 ≠ –32 (x ± 6)
9. Find the equation for a trend line
for the data at the right.
Answers may vary. Sample:
y ≠ 5.33x ± 1.34
24
x
10. y ≠ –6.07x ± 62.71
70 90
Year (19–)
b – c. Answers may
vary. Samples:
b. Let 1960 ≠ 60. Two
points on line are
(62, 18) and (90, 30).
y ≠ 0.429x – 8.6
c. y ≠ 0.429(105)
– 8.6; 36.4 million
people
356
5. x + y = 3; (5, 4) y – 4 ≠ –(x – 5)
7. y = - 4x + 2; (0, 2) y – 2 ≠ 14 x
12
356
3. (-7, -5); m = 0
4. Write an equation for the line through the points (2, -6) and (-1, -4).
y ± 6 ≠ –23 (x – 2)
Write an equation of the line that is parallel to the given line and that passes
through the given point.
y
O
2. (0, -3); m = 18
10. Graphing Calculator Use a
graphing calculator to find the
equation for the line of best
fit for the data at the right.
See left.
Chapter 6 Linear Equations and Their Graphs
[3] appropriate methods
but one computational
error
[2] incorrect points used
correctly OR points
used incorrectly;
function written
appropriately, given
previous results.
[1] correct function,
without work shown
x
1
2
3
4
5
6
7
y
7
12
19
20
28
33
40
x
1
2
3
4
5
6
7
y
54
52
45
40
33
27
18