College Algebra – Full Course
College Algebra – Full Course

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LeSSon 5-1 1. Write the relation shown in the mapping diagram

as a set of ordered pairs.

1

3

25

0

2

2. Which set of ordered pairs represents a function?

A. {(21, 4), (2, 4), (8, 4), (10, 4)}

B. {(0, 22), (3, 7), (0, 2), (18, 2)}

C. {(21, 3), (21, 21), (21, 212), (21, 0)}

D. {(1, 2), (2, 3), (3, 4), (3, 5)}

Use the table below for Items 3 and 4.

x y

18 30 3

12 2140 29

3. Explain why the relation shown in the table is not a function. Use the words input and output in your explanation.

4. How could you change the table so that the relation is a function? Explain your reasoning.

5. Model with mathematics. Darla and Albert are playing a game. Their moves are recorded on the grid shown below. Darla’s moves are indicated by X’s and Albert’s moves are indicated by O’s. Write the letter/number combinations of Darla’s moves as a set of ordered pairs.

1 2 3 4 5 6

A O XB X XC XD O Oe O

LeSSon 5-2 6. Identify the domain and range of each function.

a. {(15, 2), (3, 0), (212, 0), (21, 21), (9, 2)}

b.

x

y

1

12345

2425

2322212122232425 2 3 4 50

Algebra 1 Unit 2 Practice

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7. Reason quantitatively. A local bakery sells bagels for \$0.90 each. Consider a function for which the input is the number of bagels purchased and the output is the total cost of the bagels. What are the domain and range in this situation? Explain.

8. Which is an (input, output) ordered pair for the function machine shown below?

yxx2 2 5

A. (21, 27) B. (2, 21)

C. (3, 1) D. (5, 0)

9. a. Graph a function whose domain is {21, 0, 3} and whose range is {25, 2, 4}.

b. How many different functions have the domain and range given in part a? Explain.

10. a. Create a mapping diagram for a function whose domain has more elements than the range.

b. Is it possible to create a mapping diagram for a function whose domain has fewer elements than the range? If so, give an example. If not, explain why not.

LeSSon 5-3 11. Which shows the function y 5 x 1 1 written in

function notation?

A. f(b) 5 x 1 1 2 y

B. f(y) 5 x 1 1

C. f(x) 5 y 2 1

D. f(x) 5 x 1 1

12. Model with mathematics. Manny wants to rent a movie. Each movie costs \$1 to rent. The function f(x) 5 x represents this situation. Explain what x and f(x) represent in this situation.

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For Items 13 and 14, use the function f(x) 5 2x 1 5.

13. Evaluate the function for x 5 23, 0, 12

, and 10.

14. When asked to find the value of x for which f(x) 5 17, Hudson answered 39. What mistake did Hudson make? What is the correct answer?

15. Write a sequence for which f(3) 5 14

.

LeSSon 6-1 16. Explain why the graph shown is the graph of a

continuous function.

x

y

1

12345

21212223 2 30

y 5 2x 1 4

Use the graph below for Items 17–19.

0

100

200

300

400

500

600

10 20 30 40 50 60x

y

Minutes Since Ride Began

Hei

ght

(ft)

17. Which point corresponds to the absolute maximum of the function?

A. (20, 300) B. (50, 400)

C. (60, 0) D. (0, 0)

18. a. Make sense of problems. Use set notation to write the domain and range of the function.

b. Another balloon had the same height as the second balloon for the first 50 minutes but then took 5 minutes longer to descend. How do the domain and range for the second balloon compare to the domain and range in part a?

19. a. Identify the y-intercept. What does the y-intercept represent in this situation?

b. Would it be possible for the graph of another balloon’s height to have a different y-intercept? Explain.

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LeSSon 6-2

20. Explain how to use the graph of a function to determine the y-intercept.

Use the graph for Items 21–23.

x

y

1

12345

232221212223 2 30

21. Which statement is true?

A. This function has no relative or absolute maxima.

B. This function has a relative maximum of 5 but no absolute maximum.

C. The point corresponding to the absolute maximum is above the y-intercept.

D. The absolute maximum is 5.

22. Identify any relative or absolute minima.

23. Explain why the domain of the function is all real numbers.

24. Construct viable arguments. Rose says that the

domain of the function f xx

( )14

51

is all real

numbers. Is Rose correct? If so, explain why. If not, explain why not and give the correct domain.

LeSSon 6-3 25. A plumber charges \$65 per hour plus a \$100

inspection fee. The cost for x hours of work is given by the function f(x) 5 65x 1 100.

a. Identify the independent and dependent variables.

26. James bought a plant that was 3 inches tall. Each week the plant grew 2 inches. The function h(x) 5 2x 1 3 describes the height of the plant after x weeks. Which is the reasonable domain for this function?

A. {x: x \$ 2}

B. {x: x \$ 3}

C. {x: x \$ 0}

D. All real numbers

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Use the graph below for Items 27 and 28.

x

y

1

12345

2 3 4 5 60

27. Attend to precision. Explain why {x: x \$ 0} is not a reasonable domain.

28. Write a real-world situation that matches the graph.

LeSSon 7-1A weight of 12 ounces stretches a spring 24 inches. A weight of 18 ounces stretches the same spring 36 inches. Use this information for Items 29–33.

29. How far does the spring stretch for each additional ounce of weight?

A. 12

inch B. 32

inches

C. 2 inches D. 20 inches

30. Model with mathematics. Write a function to describe the relationship between the distance d that the spring stretches and the weight w that is attached to the spring.

32. Make a graph for this situation.

33. Kathleen says that a weight of 25 ounces will stretch the spring 45 inches. Is she correct? Describe how to check Kathleen’s answer by using the equation and by using the graph.

LeSSon 7-2The height of an object in feet t seconds after it has been dropped from a height of 1200 feet can be represented by the function h(t) 5 1200 2 16t2. Use this information for Items 34–38.

34. Make a table of values for t 5 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. What information does the table tell you about when the object reaches the ground? Explain.

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35. Which describes the reasonable range for the function?

A. 0 # h(t) # 16

B. 0 # h(t) # 1200

C. 16 # h(t) # 1200

D. 1200 # h(t) # 16

36. Use appropriate tools strategically. Use a graphing calculator to graph the function. Explain how to determine an appropriate viewing window. Make a sketch of the graph, including axis labels.

37. What is the y-intercept? Explain what the y-intercept means in the context of the problem.

38. Explain how to use the graph to estimate how many seconds it takes for the object to reach the ground. How can you use the equation to check your answer?

LeSSon 7-3

39. Denzel bought a new computer for \$540. The value of the computer decreases by 1

3 each year. Make a

table to show the value of the computer after 0, 1, 2, and 3 years.

A radioactive substance has a half-life of 2 seconds. A scientist begins with a sample of 20 grams. Use this information for Items 40–43.

40. How much of the substance remains after 8 seconds?

A. 0.625 grams B. 1.25 grams

C. 4 grams D. 10 grams

41. Reason abstractly. Explain why the amount of the substance that remains will always be greater than 0.

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42. Which graph below could represent the amount of the radioactive substance over time? Justify your answer.

A.

x

y

5

10

Am

ount

(g) 15

20

2.5 5 7.5Time (seconds)

10 12.5 150

B.

x

y

25

50

Am

ount

(g) 75

100

2.5 5 7.5Time (seconds)

10 12.5 150

43. For the graph in Item 42 that could represent the amount of a decaying radioactive substance, find the amount after 2 seconds. Describe how you used the graph to find the answer.

LeSSon 8-1

44. Describe the transformation from the graph of f(x) 5 x2 to the graph of g(x) 5 x2 2 4.

The graph of the function f(x) 5 2x is translated up 8 units to get the graph of g(x). Use this information for Items 45 and 46.

45. For each pair of values, tell which value is greater.

a. The y-coordinate of the y-intercept of g(x); the y-coordinate of the y-intercept of f(x)

b. f(2); g(2)

c. f(4); g(1)

46. The graph of h(x) is translated 12 units down from the graph of g(x). How is the graph of h(x) related to the graph of f(x)?

A. The graph of h(x) is translated 20 units down from the graph of f(x).

B. The graph of h(x) is translated 4 units down from the graph of f(x).

C. The graph of h(x) is translated 4 units up from the graph of f(x).

D. The graph of h(x) is translated 20 units up from the graph of f(x).

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47. Critique the reasoning of others. The graph shows a transformation of the function f(x) 5 x2. Brad said the equation of the function is g(x) 5 x2 1 3. Do you agree with Brad? Explain.

x

g(x)

y

1

12345

2423222121222324 2 3 4 650

48. Bart’s Bowling Alley charges \$4 for shoe rental and \$5.25 for each game bowled. Alley Cat Bowling charges \$5 for shoe rental and \$5.25 for each game bowled.

a. Write a function b(x) that describes the total cost of bowling x games at Bart’s Bowling Alley.

b. Write a function a(x) that describes the total cost of bowling x games at Alley Cat Bowling.

c. Without graphing, describe how the graphs of b(x) and a(x) are related. Use the functions you wrote in parts b and c to justify your answer.

d. How will the graph of a(x) be transformed if Alley Cat Bowling reduces the cost for shoe rental? Explain.

LeSSon 8-2

49. Describe the transformation from the graph of f(x) 5 x3 to the graph of g(x) 5 (x 1 1)3 1 12.

50. The graph of f(x) 5 x2 is translated 3 units up and 1 unit to the right to create the graph of g(x). Which is the equation of g(x)?

A. g(x) 5 (x 1 3)2 1 1

B. g(x) 5 (x 2 3)2 1 1

C. g(x) 5 (x 2 1)2 1 3

D. g(x) 5 (x 1 1)2 1 3

51. Use appropriate tools strategically. Each ordered pair below is the vertex of the graph of a function that is a transformation of the graph of f(x) 5 x2. For each vertex, write a possible function. How could you use a graph to check your answers?

a. (0, 25) b. (3, 0)

c. (6, 29) d. (22, 1)

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52. The function f(x) 5 x2 1 4 is graphed below. Without graphing, identify the vertex of the graph of g(x) 5 (x 2 5)2 1 4. Explain how you found your answer.

23x

y

1

321

45678

212122 2 30

y 5 x2 1 4

53. A golf club has a driving range. Non-members of the club may use the driving range by paying an entry fee of \$8.50 and \$5 per bucket of balls.

a. Lenny is not a member of the golf club. He went to the driving range on Saturday and hit x buckets of balls. Write a function that gives Lenny’s total cost on Saturday.

b. On Sunday, Lenny went back to the driving range and hit 3 fewer buckets of balls. How can you modify your function from part a to describe Lenny’s total cost on Sunday?

c. Without graphing, describe the transformation from the graph of the function in part a to the graph of the function in part b. Justify your answer.

LeSSon 9-1

54. Which ratio does not represent the slope of a line?

A. riserun

B.

xy

C. yx

change inchange in

D. vertical changehorizontal change

55. What is the slope of the line?

x

y

1

3

5

7

9

22

222426 0 2

y 5 3×12

56. A line has a slope of 2. Give the coordinates of two points that could be on this line. Show that your two points lie on a line with slope 2.

57. Reason abstractly and quantitatively. Line a passes through the points (21, 0) and (3, 28).

a. Find the slope of line a.

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57. b. Line b passes through the points (21, 0) and (3, y). Find a value for y for which the slope of line b is greater than the slope of line a. Justify your answer.

LeSSon 9-2 58. Look for and make use of structure. Does the

table represent data that have a constant rate of change? Justify your answer.

x y

−3 −130 −15 196 23

59. Carlos buys a phone that costs \$250. He pays a monthly rate of \$75.

a. Write a function f(x) for the total amount that Carlos pays for using the phone for x months.

b. Make a table of ordered pairs and graph your function. Remember to label your axes.

c. What is the rate of change?

d. Describe the relationships between the rate of change, the real-world situation, the equation of the function, and the graph.

60. For a linear function, which statement about slope and rate of change is true?

A. The slope is greater than the rate of change when the slope is positive.

B. The slope is equal to the rate of change.

C. There is no relationship between slope and rate of change.

D. Slope and rate of change are related, but more information is needed to describe the relationship.

61. Write a real-world situation for which the rate of change is 215.

LeSSon 9-3 62. Each situation can be described by a linear graph.

Tell whether the slope of the graph will be positive or negative. Explain your answers.

a. Sammie earns \$10 per hour.

b. Water is draining from a tank at a rate of 6 gallons per minute.

c. A car is traveling at a speed of 60 mi/h.

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63. What is the slope of the line shown in the graph?

x

y

2

4

6

8

22

2224 2 40

y 5 7

A. 27 B. 0

C. 7 D. undefined

64. Construct viable arguments. Jackson says the slope of a vertical line is 0. Describe how you would explain to Jackson why he is incorrect.

65. Name a point that lies on the same line as the line containing the points (22, 0) and (4, 10). Show how you determined your answer.

66. The function in the table is linear. What is the missing y-value? Justify your answer.

x y

23 120 ?5 246 26

LeSSon 10-1

67. The value of y varies directly with x, and the constant of variation is 6. What is the value of x when y 5 54?

A. 6 B. 9

C. 54 D. 324

68. The table represents a direct variation. Write the direct variation equation for the data.

x y

2 3

4 66 98 12

69. Dan bought 3 bags of potting soil and spent \$3.75.

a. Does this situation represent a direct variation? If not, explain why not. If so, explain why and identify the constant of variation.

b. How much would Dan spend for 7 bags of potting soil?

70. a. Attend to precision. Write a linear equation that does not represent a direct variation.

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70. b. Sketch a linear graph that does not represent a direct variation.

71. Jen says the equation 2y 2 4x 5 0 does not represent a direct variation because it is not in the form y 5 kx. How would you explain to Jen why she is incorrect?

LeSSon 10-2

72. Which equation shows an indirect variation?

A. y 5 8x B. �yx8

C. xy 5 8 D. 8y 5 x

The time needed to paint a surface varies indirectly as the number of people painting. A painting company, Color Your World, says that a team of 5 painters can paint the walls in a particular building in 8 hours. Use this information for Items 73 and 74.

73. Write and graph an indirect variation equation that relates the time to paint the building walls to the number of painters. Remember to label your axes.

74. A second painting company, Good Hues, says that they can paint the walls in the building in 6 hours with a team of 7 painters. Which painters work at a faster rate 2 the painters from Color Your World or the painters from Good Hues? Justify your answer.

75. The value of y varies indirectly with the value of x, and the constant of variation is 5. What is the value of x when y 5 10?

76. a. express regularity in repeated reasoning. Complete the table.

x y 5 x120

y 5 x160

y 5 x192

1248

b. Look for patterns in the table. In an indirect variation, what happens to the value of y when the value of x is doubled?

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LeSSon 10-3

77. Model with mathematics. Erin is starting a yard care business. A lawn mower and other supplies will cost her \$450. She plans to charge \$15 for each hour that she works.

a. Write and graph a function p(x) for the profit Erin will earn for working x hours. (Hint: Profit is equal to earnings minus expenses.)

b. What is the y-intercept of the function? Describe what the y-intercept means in terms of profit.

c. Erin estimates that an average job will take about 1.5 hours. How many jobs must Erin have to break even? Explain your answer. (Hint: Erin will break even when her profits are equal to 0.)

d. Erin wants to break even after working 10 jobs. How could Erin accomplish this?

A school is holding a craft fair as a fundraiser. An artist donates \$25 to rent a table at the fair. In addition, each artist must donate \$2 for each item sold to the school’s art program. The table shows the total amount that an artist will donate if he or she sells 0, 1, 2, and 3 items. Use this information and the table for Items 78–80.

Items 0 1 2 3

Amount Donated \$25 \$27 \$29 \$31

78. Write a function f(x) for the total amount an artist donates for selling x items.

79. If an artist sells 45 items, how much will he or she donate?

A. \$90 B. \$115

C. \$205 D. \$465

80. Mariah makes refrigerator magnets that she sells for \$3 each.

a. Would you recommend that Mariah participate in this craft fair? Why or why not?

LeSSon 10-4 81. What is the inverse of the function

f(x) 5 22x 2 1?

A. f x x( )12

11 5 2 12

B. f x x( )12

12

1 5 2 22

C. f x x( ) 2 11 5 12

D. f x x( )12

1 5 22

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82. Is the function f(x) 5 4×2 a one-to-one function? Explain using the equation and the graph.

83. The function f(x) 5 9.25x gives the cost f(x) for x tickets to a baseball game.

a. What is f–1(x)?

b. What does x represent in the inverse function?

c. Tomika spent \$46.25 on tickets. How many tickets did she buy?

The table shows the number of days in each month of the year (when the year is not a leap year). Use the table for Item 84.

January 31 July 31February 28 August 31March 31 September 30April 30 October 31May 31 November 30June 30 December 31

84. a. Write a set of ordered pairs in the form (month, days) to represent the function that assigns a number of days to each month.

b. Does the function you wrote in part a have an inverse function? Explain.

c. Describe a real-world situation that is an example of a one-to-one function. How do you know that the function is one-to-one?

85. Persevere in solving problems. Two functions, f(x) and g(x), are evaluated for several values of x, below. Could f(x) and g(x) be inverse functions? Justify your answer.

f(0) 5 3 g(1) 5 2

f(21) 5 12

g(0) 5 3

f(2) 5 5 g(3) 5 21

LeSSon 11-1

86. Which statement about the sequence 23, 18, 13, 8, 3, …, is false?

A. The sequence is arithmetic.

B. The common difference is 5.

C. a3 5 13

D. The 8th term is 212.

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87. Critique the reasoning of others. Carlotta says the sequence below is an arithmetic sequence because you multiply each term by 2 to get the next term. Is Carlotta correct? Explain.

2, 4, 8, 16, 20, …

88. Identify the common difference in each arithmetic sequence.

a. 21, 15, 9, 3, 23, …

b. 22, �32

, 21, �12

, 0, …

c. –19, –9, 1, 11, 21, …

89. Consider a sequence in which every term is the same. Is the sequence an arithmetic sequence? Explain.

LeSSon 11-2Three arithmetic sequences are described below. Use the sequences for Items 90–92.

Sequence 1

22, 33, 44, 55, 66, …

Sequence 2

an 5 2.5 1 6(n 2 1)

Sequence 3

x

y

1

123456789

10111213

2 3 4 50

14

90. Which sequence has the greatest common difference?

91. Which sequence has the least value for a10?

92. Which statement is true?

A. Sequence 2 has the greatest first term.

B. The 8th term of Sequence 3 is greater than the 6th term of Sequence 2.

C. The first four terms of Sequence 3 are 1, 2, 3, and 4.

D. A graph of Sequence 1 would have a slope of 11.

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93. Model with mathematics. Antonio is arranging tiles according to the pattern below.

Stage 1 Stage 2 Stage 3

Write the explicit formula for the arithmetic sequence that models Antonio’s pattern. Explain what the values of an and d represent in the context of the situation.

94. Write an arithmetic sequence for which a4 5 11 and a9 5 36. Write the explicit formula for the sequence, and graph it. Explain how you found your answer.

LeSSon 11-3 95. Write a function to describe the arithmetic

sequence 23, 2, 7, 12, 19, ….

96. For the arithmetic sequence graphed below, find f(2) and f(11).

x

y

1

1

2122

234567

21 2 3 4 5 6 7 8 90

97. What ordered pair represents the nth term of the sequence shown?

14, 23, 32, 41, 50, …

A. (n, 5 1 n) B. (n, 14 1 9n)

C. (n, 5 1 9n) D. (n, 9n)

98. The 3rd term of an arithmetic sequence is 212, and the 7th term is 0. As a first step in writing a function for this sequence, Luisa found the slope of the line that contains the points (3, 212) and (7, 0).

a. Does Luisa’s first step make sense? Explain what Luisa might be thinking.

b. Write a function to model this sequence.

99. Make sense of problems. An arithmetic sequence is given by the function f(n) 5 3n 2 1.

a. What is the inverse of this function, f 21(n)?

b. What are the inputs and outputs of the inverse function?

c. Write a question that could be answered using the inverse function, and show how to use the inverse function to answer your question.

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LeSSon 11-4

100. An arithmetic sequence is described by the

recursive formula �

� ��

aa a

27n n

1

1. If an21 5 1, what

is the value of an?

A. 2 B. 3

C. 7 D. 8

101. Find the recursive formula for each arithmetic sequence. Include the recursive formula in function notation.

a. 12,54, 2,

114, …

b. an 5 2n 2 5

c. The arithmetic sequence for which a1 5 5 and a8 5 33

d.

x

y

1

2468

10

2102826242221 2 3 4 650

102. Construct viable arguments. Does the function shown represent an arithmetic sequence? Justify your answer.

� � �⋅

ff n f n(1) 1( ) 2 ( 1) 6

103. Why is it important for a recursive formula to identify the first term? For example, why isn’t an 5 an 2 1 2 3 sufficient to define a sequence?

LeSSon 12-1

104. Which equation describes the line with slope 23

and y-intercept

0,

12

?

A. y x12

352 1

B. y x12

352 2

C. y x312

52 2

D. y x312

52 1

105. Write the equation in slope-intercept form of the line with the same slope as the line described by 8x 1 2y 5 17 and the same y-intercept as the line described by 2x 1 y 5 1.

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106. Look for and make use of structure. Write an equation of the line represented by the data in the table.

x y

−2 00 −12 −2

107. Laura opened a savings account with an initial deposit of \$200. Each month she adds \$50 to the account. Now she has \$650.

a. Write an equation in slope-intercept form that gives the total amount Laura has in her savings account after x months.

b. How many months has Laura been putting money into the account? Explain your answer.

c. Laura’s brother also opened a savings account with \$200, but his monthly deposit is not the same as Laura’s. Describe the similarities and differences between the equation and graph describing the amount of money in Laura’s account and the equation and graph describing the amount of money in her brother’s account.

108. The following problem appeared on Kris’s math quiz:

The equation of a line is y 5 mx 2 5 and (22, 3) is on the line. Find the value of m and write the equation of this line.

Kris says he cannot find the equation because he does not know the slope. Explain how Kris can find the slope. What is the equation of the line?

LeSSon 12-2

109. The slope of a line is 15 and the point (3, 21) lies on the line. Write an equation of the line in point-slope form.

Use the graph for Items 110–112.

x

y

1

123

2223

21221222324 2 3

(3, 1)

(21, 21)

4 50

2x 12y521

110. Write an equation of the line in point-slope form.

111. How many different equations in point-slope form can be written for the line? Explain.

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112. How many different equations in slope-intercept form can be written for the line? Explain.

113. Rosa pays a monthly membership fee at a gym. She also pays \$5 for each cycling class she takes. In May, she took 4 cycling classes and her total cost for the month was \$55. In June, Rosa’s total cost was equal to twice the membership fee. How many cycling classes did Rosa take in June?

A. 5 B. 6

C. 7 D. 8

114. Use appropriate tools strategically. Will says you cannot use a graphing calculator to graph a line when the equation is in point-slope form. Explain Will’s reasoning. How could you modify an equation given in point-slope form so that you could graph the line on a graphing calculator? Use the equation y 2 2 5 23(x 1 5) as an example in your explanation.

LeSSon 12-3

115. Determine the x-intercept, y-intercept, and slope of the line described by 4x 1 7y 5 228.

116. Which shows the equation of the line 4y 5 3(x 2 21) written in standard form?

A. 23x 1 4y 5 263

B. 23x 1 4y 5 221

C. 3x 2 4y 5 63

D. 23x 2 4y 5 21

117. Chase says that x 5 3 is the equation in standard form for the horizontal line that passes through the point (3, 5). What mistake did Chase make? What is the correct equation in standard form for this line?

118. Several linear equations are shown below. Arrange the equations a2h in order from least slope to greatest slope.

a. y 5 12

x 1 7 b. 2x 2 5y 5 10

c. y 2 2 5 3(x 2 4) d. x 2 3y 5 6

e. y 2 2 5 � �x12( 1) f. y 5 2x

g. y 1 3 5 22(x 1 1) h. 3x 1 y 5 5

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119. Model with mathematics. A nursery sells purple basil plants and green basil plants. Each purple plant sells for \$4. Each green plant sells for \$3.75. Clara has \$50 to spend on basil plants. Let x represent the number of purple plants and let y represent the number of green plants. Write an equation in standard form that models this situation.

LeSSon 12-4

120. Which equation describes a line that is parallel to

the graph of y x34

15 1 ?

A. 3x 1 4y 5 1

B. 4y 5 3x 2 18

C. 23y 5 4x 2 2

D. y 2 8 5 � �x43( 2)

121. Persevere in solving problems. For what value(s) of a are the lines described by 2x 1 3y 5 6 and ay 5 6x 1 10 perpendicular? Explain.

122. a. Write an equation of a line that is parallel to the line containing the points (0, 27) and (5, 12).

b. Is there more than one possible answer to part a? If so, explain why and give another possible answer. If not, explain why not.

123. a. Write an equation of a line that is perpendicular to the line described by y 2 2 5 2x 1 8 and that contains the point (21, 12).

b. Is there more than one possible answer to part a? If so, explain why and give another possible answer. If not, explain why not.

LeSSon 13-1

124. Which equation best models the data displayed in the scatter plot?

x

y

1

123456789

222121223 2 3 4 5 6 7 802

A. y 5 2x

B. y 5 23x 1 1

C. y 5 x 1 2

D. y 5 4x

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The table shows the finish times for runners in a race and the number of months that each runner spent training for the race. Use the table for Items 125–128.

Months of Training

3 2 1 6 6 6 2

Finishing Times (min)

45 50 65 38 40 45 58

125. Describe how the finishing times change as the months of training increase.

126. Make a scatter plot using the months of training as the independent variable.

127. Draw a trend line on your scatter plot. Identify two points on your trend line and write an equation for the line containing those two points.

128. Critique the reasoning of others. Josie predicted that a runner who trained for 8 months would have a finishing time of 30 minutes. Is Josie’s prediction reasonable? Explain.

LeSSon 13-2

129. Which pair of quantities most likely does not show a positive correlation?

A. The age of a baby and the weight of the baby

B. The length of a car trip and the amount of gas required for the trip

C. Students’ test scores and the number of hours the students spent studying for the test

D. The number of cups of milk a person drinks each day and the number of vacation days the person has each year

The director of a public pool keeps records on the daily high temperature and the number of people at the pool each day. Some of the director’s data is shown in the table below. Use the table for Items 130 and 131.

Temperature °F 78 86 95 98 101

number of People 85 120 245 289 329

130. a. Describe the correlation between the variables as positive, negative, or none. Justify your answer.

b. Is there causation between the variables? Explain.

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131. a. Use appropriate tools strategically. Use a graphing calculator to find the equation of the line of best fit. Round values to the nearest hundredth.

b. Predict the number of people at the pool when the temperature is 75° F.

132. Give an example of two variables for which there is a correlation but no causation. Explain.

LeSSon 13-3Jackson’s grandmother bought a painting 25 years ago for \$675. The table shows the value of the painting through the years. Use the table for Items 133–135.

Years Since Purchase 5 10 15 20 25

Value (\$) 725 800 900 975 1100

133. Which statement about the correlation between the quantities in the table is most accurate?

A. There is a negative correlation because the data do not show a constant rate of change.

B. There is a positive correlation because the painting’s value increases as time passes.

C. There is a positive correlation because negative values do not make sense for either variable.

D. There is no correlation.

134. Is there causation between the two variables? Explain.

135. a. Model with mathematics. Use a graphing calculator to find a quadratic equation that models the data. Round values to the nearest hundredth. Use the equation to predict the value of the painting after 50 years.

b. Use a graphing calculator to find an exponential equation that models the data. Round values to the nearest hundredth. Use the equation to predict the value of the painting after 50 years.

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