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Chapter 14 Skills Practice • 815

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Lesson 14.1 Skills Practice

Name _______________________________________________________Date _________________________

Where Do You Buy Your Books?Drawing Lines of Best Fit

VocabularyDefine each term in your own words.

1. line of best fit

2. model

816 • Chapter 14 Skills Practice

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Lesson 14.1 Skills Practice page 2

Problem SetCreate a scatter plot representing the table on each given grid. Be sure to label your graph clearly.

1. Beagle’s Weight (female)

Age (in weeks) Weight (in kg)

6 1.0

12 3.0

16 4.5

24 6.5

30 8.0

x3024 27

6

7

8

9

10

12 15

4

5

18 210

3

3 6 9

2

1

y

Age (in weeks)

Beagle’s Weight (Female)

Wei

ght (

in k

g)

2. Beagle’s Weight (male)


6 1.0

12 3.5

16 5.0

24 7.0

30 9.0


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Name ________________________________________________________ Date _________________________

3. Chihuahua’s Weight (male)

Age (in weeks) Weight (in oz)

6 15

12 30

16 39

24 46

30 51

4. Chihuahua’s Weight (female)


6 11

12 19

16 25

20 30

24 33


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5. Dalmatian’s Weight


8 6.5

12 11.5

16 15.4

20 21.5

25 24.5

6. Pomeranian’s Weight


6 13

12 22.5

16 30

20 35.5

24 39


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Name ________________________________________________________ Date _________________________

Use a ruler to draw a line that best fits each scatter plot.

7.

x2520

15

20

25

10

10

150 5

5

y 8.

x2520

15

20

25

10

10

150 5

5

y

9.

x2520

15

20

25

10

10

150 5

5

y 10.

x2520

15

20

25

10

10

150 5

5

y


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11.

x0 5 10 15 20 25

5

10

15

20

25

y 12.

x0 5 10 15 20 25

5

10

15

20

25

y

Draw a line of best fit for each scatter plot. Then write the equation of the line.

13. (0, 18), (5, 16), (7, 10), (10, 8), 14. (0, 10), (5, 5), (6, 4),

(15, 3), (20, 0) (7, 3), (10, 0)

x2520

15

20

25

10

10

150 5

5

y

x

2520

15

20

25

10

10

150 5

5

y

Sample Answer: y 5 2 9 ___ 10 x 1 18



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15. (0, 0), (1, 2), (2, 4), (3, 6), (5, 10) 16. (0, 0), (5, 5), (7, 8), (8, 6), (10, 10)

x2520

15

20

25

10

10

150 5

5

y

x2520

15

20

25

10

10

150 5

5

y

17. (0, 15), (5, 13), (10, 15), (15, 10), (25, 10) 18. (0, 10), (5, 14), (10, 15), (15, 16), (20, 20)

x0 5 10 15 20 25

5

10

15

20

25

y

x0 5 10 15 20 25

5

10

15

20

25

y


Name ________________________________________________________ Date _________________________


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Use the given equation to answer each question.

19. A grocery store’s earnings in dollars can be modeled by the equation y 5 0.75x 2 0.15x, where

x represents the number of tomatoes that they sell. If they sell 200 tomatoes in one day, how much

money do they earn?

y 5 0.75(200) 2 0.15(200)

5 150 2 30

5 120

The grocery store earns $120 if they sell 200 tomatoes.

20. The number of T-shirts that a T-shirt company sells can be modeled by the equation

y 5 218x 1 520, where the price of a T-shirt is represented by x. If they sell their T-shirts

for $8 each, how many will they sell?


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Name ________________________________________________________ Date _________________________

21. The distance a car can travel in miles is modeled by the equation y 5 23x 2 6, where x represents

the number of gallons of gas the car uses. If the car traveled 86 miles, how many gallons of gas did

it use?

22. The amount a shoe store charges in dollars to deliver x pairs of shoes can be modeled by the

equation y 5 40x 1 30. If the total bill was $350 dollars, how many pairs of shoes did they deliver?


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23. The number of gallons of water, y, in a swimming pool is modeled by the equation y 5 7.5x 1 500,

where x represents the time in minutes after the pump is turned on. How many gallons of water are

in the pool if the pump runs for 200 minutes?

24. The height of a tree, y, is modeled by the equation y 5 2.5x 1 3, where x represents the age of the

tree in years. How old will the tree be when it is 33 feet tall?


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Mia Is Growing Like a Weed!Analyzing the Line of Best Fit

Problem SetEstimate the equation of the line of best fit shown in each scatter plot.

1.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 2 4 6

4

6

2

y

Answers will vary but should be close to the following equation.

m 5 y2 2 y1 _______ x2 2 x1

5 2 2 17 _______ 0.5 2 8

5 215 _____ 27.5

5 2

y 2 y1 5 m(x 2 x1)

y 2 1 5 2(x 2 0)

y 5 2x 1 1


Name ________________________________________________________ Date _________________________


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2.

x2016 18

12

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16

18

20

8 10

8

10

12 140 2 4 6

4

6

2

y



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3.

x2016 18

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14

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18

20

8 10

8

10

12 140 2 4 6

4

6

2

y


Name ________________________________________________________ Date _________________________


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4.

x2016 18

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14

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18

20

8 10

8

10

12 140 2 4 6

4

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5.

x2016 18

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8 10

8

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12 140 2 4 6

4

6

2

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Name ________________________________________________________ Date _________________________


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6.

x2016 18

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18

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8

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12 140 2 4 6

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Name ________________________________________________________ Date _________________________

Use each given line of best fit to make each prediction.

7. Predict the 2005 mathematics SAT score for Connecticut.

Connecticut SAT Scores: Mathematics

508509510511512513514515516

1999 2000

Source: The College Board

2001 2002 2003 2004 2005

Year

SA

T S

core

Answers will vary. I predict the 2005 mathematics SAT score for Connecticut is

approximately 516.

8. Predict the 2005 mathematics SAT score for New York.

New York SAT Scores: Mathematics

504505506507508509510511

1999 2000 2001 2002 2003 2004 2005

Year

SA

T S

core

Source: The College Board


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9. Predict the average monthly number of sun spots that occurred in 2001.

Average Monthly Sun Spots: 1995–2000

0

20

40

60

80

100

120

140

1994 1995 1996 1997 1998 1999 2000 2001

Year

Num

ber

of S

un S

pots

Source: National Geophysical Data Center

10. Predict the average monthly sun spots that occurred in 1905.

Average Monthly Sun Spots: 1900–1904

-5

5

15

25

35

45

55

1899 1900 1901 1902 1903 1904 1905

Year

Num

ber

of S

un S

pots

Source: National Geophysical Data Center


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Name ________________________________________________________ Date _________________________

11. Predict the air temperature at an altitude of 9000 feet.

400 1000 2000 3000 4000 5000 6000 7000 8000 9000

50

60

70

80

90

100

Tem

per

atur

e ( o

F )

Altitude (feet)

Air Temperature at Different Altitudes

12. Predict the theme park’s profit in the year 2007.

252000 2001 2002 2003 2004 2005 2006 2007

30

35

40

45

50

55

60

pro

fit

(mill

ions

of

do

llars

)

Year

Theme Park Profits


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Compare each of the given graphs to determine which line is a better fit for the data.

13. Gold Prices

$0.00$100.00$200.00$300.00$400.00$500.00$600.00$700.00$800.00$900.00

$1,000.00

2003 2004 2005

Graph A

2006 2007 2008 2009

Year

Gol

d P

rices

Gold Prices

$0.00$100.00$200.00$300.00$400.00$500.00$600.00$700.00$800.00$900.00

$1,000.00

2003 2004 2005 2006 2007 2008 2009

Year

Gol

d P

rices

Graph B

Graph B is a better choice for the line of best fit. Graph B has the same number of points above

the line as it has below the line and the most points that cluster to the line of best fit.

14. Gold Prices

$250.00$270.00$290.00$310.00$330.00$350.00$370.00$390.00$410.00$430.00

1999 2000 2001 2002 2003 2004 2005

Year

Gol

d P

rice

Graph A

Gold Prices

$250.00$270.00$290.00$310.00$330.00$350.00$370.00$390.00$410.00$430.00

1999 2000 2001 2002 2003 2004 2005

Year

Gol

d P

rice

Graph B


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Name ________________________________________________________ Date _________________________

15. U.S. Gasoline Prices per Gallon

$1.50

$2.00

$2.50

$3.00

$3.50

$4.00

$4.50

Jun 2008 Sep 2008 Dec 2008 Mar 2009

Date

Pric

e pe

r G

allo

n

Graph A

U.S. Gasoline Prices per Gallon

$1.50

$2.00

$2.50

$3.00

$3.50

$4.00

$4.50

Jun 2008 Sep 2008 Dec 2008 Mar 2009

Date

Pric

e pe

r G

allo

n

Graph B

16. U.S. Gasoline Prices per Gallon

$2.50$2.75$3.00$3.25$3.50$3.75$4.00$4.25

Apr2007

Aug2007

Nov2007

Feb2008

Jun2008

Sep2008

Date

Pric

e pe

r G

allo

n

Graph A

U.S. Gasoline Prices per Gallon

$2.50$2.75$3.00$3.25$3.50$3.75$4.00$4.25

Apr2007

Aug2007

Nov2007

Feb2008

Jun2008

Sep2008

Date

Pric

e pe

r G

allo

n

Graph B


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17.

100

120

140

160

180

200

220

1980 1982 1984 1986 1988 1990 1992 1994

Num

ber

of

Elk

YearGraph A

Elk Population on Animal Preserve

100

120

140

160

180

200

220

1980 1982 1984 1986 1988 1990 1992 1994

Num

ber

of

Elk

YearGraph B


18.

100

120

140

160

180

200

220

1992 1994 1996 1998 2000 2002 2004 2006

Num

ber

of

Elk

YearGraph A


100

120

140

160

180

200

220

1992 1994 1996 1998 2000 2002 2004 2006

Num

ber

of

Elk

YearGraph B


Use the given equation to answer each question.

19. A computer parts company estimates its profit, y, using the equation y 5 0.85x 2 125, where

x is the number of parts they sell. If they sell 200 parts to computer repair store A and 160 parts to

computer repair store B, what was the parts company’s profit?

Total parts sold: 200 1 160 5 360

y 5 0.85(360) 2 125 5 306 2 125 5 181

The parts company made about $181 in profit.


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Name ________________________________________________________ Date _________________________

20. A restaurant uses the equation y 5 35x 2 325 to approximate its profit, y, for a day, where x is the

number of customers. On Friday, if they have 11 customers for lunch and 25 customers for dinner,

how much did they earn in profit?

21. An artist’s paintings increase in price as he becomes more popular. He estimates the price, y, of each

painting using the equation y 5 0.75x 1 300, where x is the number of paintings he has already sold.

If his latest painting is selling for $317.25, how many paintings has he already sold?

22. Your grandmother gives you money for college every year. She determines the amount, y, based

on your age, x, using the equation y 5 15x 1 45. How old will you be when she gives you $270?


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Stroop TestPerforming an Experiment

Problem SetCreate a scatter plot of the ordered pairs on each grid provided, and estimate the equation of the line of

best fit. Use your equation to answer the question. Be sure to label your graph clearly.

1. Your little sister’s classroom has a pet baby turtle. They let it swim in a tank and record its distance

at certain times. Using your line of best fit, predict how far the baby turtle will swim in 30 seconds.

Tracking a Turtle

Time (in seconds)

Distance (in meters)

5 3

6 3.3

10 4.1

11 4.5

15 6.3

20 7.9

x2016 18

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14

16

18

20

8 10Time (in seconds)

8

10

Dis

tanc

e (in

met

ers)

12 140 4 62

4

6

2

y


Name ________________________________________________________ Date _________________________

Answers for line of best fit will vary.

Sample line of best fit using first and last

data points:

y 5 mx 1 b

m 5 7.9 2 3 _______ 20 2 5

5 4.9 ___ 15

< 0.33

3 5 0.33(5) 1 b

3 5 1.65 1 b

b 5 1.35

y 5 0.33x 1 1.35

Sample solution to distance traveled after

30 seconds:

y 5 0.33(30) 1 1.35

5 11.25

In 30 seconds, the turtle will swim

approximately 11.25 meters.


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2. Your class conducts an experiment. You ask shoppers at different stores how much change they

have, and you record the total number of shoppers and the total dollar amount of change among

them. If you encountered 25 shoppers, how much change, in dollars, would you expect them to

have altogether? Use your line of best fit to approximate a solution.

Counting Change

Number of Shoppers

Total Change (in dollars)

2 1.5

5 3

7 4.2

10 4.5

14 7

18 11



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3. Jeremiah prints his digital pictures. After they start printing, he starts recording the time elapsed

and the total number of pictures printed. Using your line of best fit, if he prints 30 pictures,

approximately how much time, in seconds, will it take?

Printing Pictures

Time (in seconds)

Number of Pictures Printed

7 6.5

12 9.4

15 11.5

17 13.2

20 15

22 17.3


Name ________________________________________________________ Date _________________________


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4. A fundraiser uses telemarketers to raise money. Every so often, they stop to determine how many

phone calls they’ve made and how much money they’ve collected. Using your line of best fit, if the

telemarketers raised $250, approximately how many phone calls did they make?

Fundraising Totals

Number of Phone Calls

Money Collected (in dollars)

5 60

10 82.30

12 92

13 98.70

15 100.30

20 146


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Name ________________________________________________________ Date _________________________

Write an equation for each line of best fit.

5.

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6

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y


m 5 y2 2 y1 _______ x2 2 x1

5 6 2 5 ________ 12 2 10

5 1 __ 2

5 0.5

y 2 y1 5 m(x 2 x1)

y 2 5 5 0.5(x 2 10)

y 5 0.5x


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6.

x2016 18

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Name ________________________________________________________ Date _________________________

7.

x2016 18

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8

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8.

x2016 18

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Name ________________________________________________________ Date _________________________

Use each given equation to answer the question.

9. Your sister is moving into a new apartment. To estimate her average heating cost each month

in dollars, she uses the equation y 5 0.14x, where x is the square footage of her apartment.

How much more will it cost her to heat an apartment that is 900 square feet than one that is

700 square feet?

Difference in square footage: 900 ft2 2 700 ft2 5 200 ft2

Cost to heat this extra square footage: y 5 0.14(200)

5 $28

She estimates it will cost her $28 more per month to heat the 900 square foot apartment than

the 700 square foot apartment.

10. Your brother has found a new apartment to rent. It is 800 square feet, and the electricity cost, in

dollars per month, will be approximately y 5 0.08x, where x is the square footage of the apartment.

He doesn’t want to pay more than $60 a month for electricity. Should he rent this apartment?


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11. Alice and Monique run a race. Alice’s distance in meters can be approximated using the equation

a 5 6x and Monique’s distance in meters can be approximated using the equation m 5 7x, where

x is the time in seconds. If the two girls raced in a 400-meter sprint, who would finish first?

12. Francis and Mario are competing in a 200-meter sprint. Francis’s distance in meters can be

approximated by the equation f 5 9.09x and Mario’s distance can be approximated by the

equation m 5 8.89x, where x is the time in seconds. Who would win the 200-meter race between

the two boys?


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Name ________________________________________________________ Date _________________________

Use the given information about the experiments to answer each question.

13. A professor is interested in determining the average reading time of his students. He performs two

experiments. In the first experiment, students read in a quiet room and are uninterrupted. In the

second experiment, students read in a busy cafeteria.

The line of best fit for the first experiment is w 5 259.5t 2 53.2, and the line of best fit for the

second experiment is w 5 178.8t 1 12, where w equals the total number of words read and t is

the time in minutes. Explain the difference between the number of words read in 20 minutes by a

student in each experiment.

Experiment 1:

w 5 259.5(20) 2 53.2

5 5136.8

Experiment 2:

w 5 178.8(20) 1 12

5 3576 1 12

5 3588

The difference between the number of words read by a student in experiment 1 and a student

in experiment 2 is 5136.8 2 3588 5 1548.8 words. A student in the first experiment reads 1548.8

more words than a student in the second experiment. A student in the first experiment is

reading in a quiet room and should be able to read at a faster rate than a student who is reading

in a busy cafeteria. Because students in the first experiment read at a faster rate, they will read

more words in the same amount of time.


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14. A car review website wants to compare the total gas used between small cars and pick-up trucks.

They conduct two experiments. In the first experiment, they record the number of miles driven

and the total gas used by small cars. In the second experiment, they record the number of miles

driven and the total gas used by pick-up trucks. The line of best fit for the first experiment is

d 5 29.4g 2 3.9, and the line of best fit for the second experiment is d 5 17.4g 2 2.2, where

d equals the total number of miles driven and g is the amount of gasoline in gallons. Explain the

difference between the number of miles driven by a small car and a pick-up truck if both vehicles

use 10 gallons of gasoline.


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Name ________________________________________________________ Date _________________________

15. A teacher wants to determine how far her students travel to school. She collects the times

and distances traveled for students who walk, and she separately collects the times and

distances traveled for students who ride the bus. For the students who walk, the line of best fit is

d 5 2.5t 2 0.15, and for students that ride the bus, the line of best fit is d 5 17.6t 2 0.7, where d is

the distance in miles and t is the time in hours. If two students, one walking and one riding the bus,

take 15 minutes (or 0.25 hour) to get to school, how much farther does the student travel who

rides the bus?


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16. Two experiments are conducted to compare how long it takes inkjet printers to print in

black-and-white and how long it takes them to print in color. The number of pages printed using

black-and-white can be expressed by the line of best fit p 5 33.8t 1 5.3, and the number of

pages printed using color can be expressed by the line of best fit p 5 21t 1 2.7, where p is the

total number of pages printed and t is the time in minutes. If you only have 15 minutes to use an

inkjet printer, how many more black-and-white pages could you print than color pages?


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Human Chain: Shoulder ExperimentUsing Technology to Determine a Linear Regression Equation

Problem SetFor the given value of each correlation coefficient r, indicate how close the data are to being in a

straight line.

1. r 5 0.1

The data are not close to being in a straight line because the value of r is closer to 0

than to 1.

2. r 5 0.9

3. r 5 20.1

4. r 5 20.9

5. r 5 0.4

6. r 5 20.4


Name ________________________________________________________ Date _________________________


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Use your graphing calculator to determine the linear regression equation for each of the given data

values. Write the values for a, b, r 2, and r that are provided by your calculator. Explain your results.

7. (1, 6) and (2, 22)

y 5 ax 1 b

a 5 28

b 5 14

r 2 5 1

r 5 21

The linear regression equation is y 5 28x 1 14. The values of r 2 and r show that the data are in

a straight line through the two points with a negative slope.

8. (3, 4) and (4, 5)



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9. (1, 4), (3, 11), (5, 10), and (7, 15)

10. (1, 3), (3, 6), (4, 6), and (10, 2)


Name ________________________________________________________ Date _________________________


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11. (10, 3), (8, 6), (5, 6), and (1, 2)

12. (30, 6.77), (45, 11.08), (8, 2.17), and (20, 4.63)



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Use your graphing calculator and the data from each table to calculate the linear regression equation.

Round to the nearest hundredth, if necessary.

13. The daily recommended hours of sleep by one source for different ages are listed below.

Average Number of Hours of Sleep Needed by Age

Age (in years) Hours of Sleep

0.5 15

1.5 12.5

4 11.5

9 10

15 10

20 8

Answers will vary but should be close to the equation y 5 20.28x 1 13.50.


Name ________________________________________________________ Date _________________________


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14. An office records the number of bagels that were consumed by different numbers of employees.

Number of Bagels Consumed by Employees

Number of Employees

Number of Bagels Consumed

1 1

3 2

5 5

6 7

9 8

14 10

17 15



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15. A school cafeteria records the number of students in the cafeteria and the number of hot lunches

that were purchased.

Hot Lunches Purchased by Students

Number of Students

Number of Hot Lunches Purchased

120 87

315 208

411 270

459 300

502 360

530 350

603 399


Name ________________________________________________________ Date _________________________


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16. A class records the total number of papers written and the total number of English classes taken

by each student.

Number of Papers Written per Student

Number of English Classes Taken Number of Papers Written

2 9

2 10

3 16

4 18

4 22

5 30

5 27



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Use the graphing calculator equations to write each corresponding linear regression equation. Then,

use the linear regression equation to answer the question.

17. A research company collected data to study the relationship between the total number of hours

students spend studying per week, x, and their average test grade out of 100, y. The equations

below approximate the graphing calculator output when determining the linear regression equation

for these data.

y 5 ax 1 b

a 5 2.21

b 5 66.7

r 2 5 0.96

r 5 0.98

If a student studied for 5 hours in one week, what would you expect her average test grade to be

for that week?

y 5 2.21x 1 66.7

y 5 2.21(5) 1 66.7

5 11.05 1 66.7

5 77.75

Their average test grade for that week would be approximately 77.75.


Name ________________________________________________________ Date _________________________


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18. A pet store collects data to study the number of fancy goldfish per tank, x, and the size of each tank

in gallons, y. The equations below approximate the graphing calculator output when determining the

linear regression equation for these data.

If you buy 4 fancy goldfish, what is a good estimate for the size of tank that you should buy?

Round to the nearest gallon.

y 5 ax 1 b

a 5 7.77

b 5 0.89

r 2 5 0.998

r 5 0.999


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Name ________________________________________________________ Date _________________________

19. You record the number of hours that you sleep per night, x, and your average test grade out of 100,

y, on the next school day. The equations below approximate the graphing calculator output when

determining the linear regression equation for these data.

y 5 ax 1 b

a 5 5

b 5 57.86

r 2 5 0.99

r 5 0.995

If you need to average at least 85 on a test tomorrow, how much sleep should you get tonight?

Round to the nearest half hour.


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20. A company surveyed its employees and asked them the number of vacation days they

used per year, x, and the number of places they visited that year, y. The equations below

approximate the graphing calculator output when determining the linear regression equation for

these data.

y 5 ax 1 b

a 5 0.421

b 5 20.34

r 2 5 0.913

r 5 0.955

If you want to visit at least 3 different places next year, how many vacation days should you plan

on using, according to the data in the survey? Round to the nearest number of whole days.


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Name ________________________________________________________ Date _________________________

JumpingCorrelation

VocabularyDraw a graph to illustrate each term. Estimate the value of the correlation coefficient for the graph

you drew.

1. positive correlation 2. negative correlation


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3. no correlation

Problem SetDetermine whether the points in each scatter plot have a positive correlation, a negative correlation, or

no correlation. Explain your answer.

1.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y 2.

x2520

15

20

25

10

10

150 5

5

y

The points in this scatter plot have a

negative correlation because the line

of best fit has a negative slope.


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Name ________________________________________________________ Date _________________________

3.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y 4.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y

5.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y 6.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y


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7.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y 8.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y

9.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y 10.

x2016 18

12

14

16

18

20

8 10

8

10

12 140 4 62

4

6

2

y


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Name ________________________________________________________ Date _________________________

Use a ruler to draw the line that best fits each data represented in each scatter plot. Explain what your

graph and line of best fit indicate about the relationship between the two variables.

11. Unemployment Rates (1992–2000)

4

4.5

5

5.5

6

6.5

7

7.5

8

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Year

Per

cent

of P

eopl

e U

nem

ploy

ed

(ove

r 16

yea

rs o

ld)

x

y

The negative slope indicates there is a negative correlation between these two variables.

The percent of people unemployed in the United States steadily decreased between

1992 and 2000.

12. U.S. Unemployment Rates: 2000–2004

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

1999 2000 2001 2002 2003 2004 2005

Year

Per

cent

age

of P

eopl

e U

nem

ploy

ed

(ove

r 16

yea

rs o

ld)

x

y


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13. Price of Electricity (1979–1996)

0

10

20

30

40

50

60

1975 1980 1985 1990 1995 2000Year

Pric

e pe

r 50

0 kw

hs

x

y

14. U.S. Hurricanes

0

2

4

6

8

10

12

14

16

18

1951–1960 1961–1970 1971–1980 1981–1990 1991–2000Year

Num

ber

of H

urric

anes

x

y


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Name ________________________________________________________ Date _________________________

Estimate the equation of the line of best fit for each scatter plot shown.

15.

x3024 27

6

7

8

9

10

12 15

4

5

18 210 6 93

2

3

1

y


m 5 y2 2 y1 _______ x2 2 x1

5 5.5 2 2 _______ 20 2 8

5 3.5 ___ 12

< 0.29

y 2 y1 5 m(x 2 x1)

y 2 2 5 0.29(x 2 8)

y 5 0.29x 2 0.32


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Name ________________________________________________________ Date _________________________

17.

x2016 18

120

140

160

180

200

8 10

80

100

12 140 4 62

40

60

20

y


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Name ________________________________________________________ Date _________________________

19.

x108 9

6

7

8

9

10

4 5

4

5

6 70 2 31

2

3

1

y


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Name ________________________________________________________ Date _________________________

Use each given equation to answer each question.

21. The average speed of a cheetah is 72 miles per hour. The total distance traveled by a cheetah is

given by the equation d 5 72h, where h is the number of hours. If cheetahs can only maintain this

speed for a total distance of 3.5 miles, for how long can they run at a speed of 72 miles per hour?

Round your answer to the nearest hundredth.

3.5 5 72h

3.5 ___ 72 5 72h ____ 72

h < 0.05

Cheetahs can run at a speed of 72 miles per hour for approximately 0.05 hour

(or approximately 3 minutes).

22. A gazelle runs at an average speed of 35 miles per hour. The total distance traveled by the gazelle

is given by the equation d 5 35h, where h represents the time in hours. If the gazelle’s total

distance traveled is 3.5 miles, for how long did it run?


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23. You make an investment of $50 in your friend’s business. According to your friend, you will have a

total of p 5 50 1 0.5m dollars if you invest in the business for m months. After 24 months, what is

your investment worth?

24. Your uncle put aside some college savings for you when you were born. The total amount saved is

A 5 5000 1 150y, where y is the time in years. If you go to college when you are 18 years old, how

much money will you have for college?

where do you buy your books? - chamblee middle...

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