7th Grade Math

Selected Answers and Solutions R29

Selected Answers and Solutions

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7. bones in wrist: 8; bones in fi ngers: 14; bones in
   palm: 5 9. Sample answer: Because the graph is
   being used to predict, straight axes, equally spaced
   scales, and accurate plotting of points are necessary
   to get the most accurate prediction.

Pages 536–539 Lesson 9-4B

1a. Sample answer: The graph shows a positive

relationship. That is, as the years pass, the

population increases.

1b.

Number of People

20002001200220032004200520062007

40,000

38,000

36,000

34,000

32,000

30,000

28,000

26,000

24,000

22,000

20,000

Year

Population of Fayette County

1c. Sample answer: 40,000

33 a. Every two minutes, Ciro climbs about

50 steps. After 10 minutes, he has climbed just

under 300 steps, so in 12 minutes he will have

climbed just under 350 steps. So, 13 minutes is a

good prediction for 354 steps.

3b. Every two minutes, Ciro climbs about 50 steps.

After 10 minutes, he has climbed just under

300 steps, so in 14 minutes he should have climbed

about 400 steps. 3c. positive relationship

5a.

Math Scores

5678910

Hours of Sleep

100

95

90

85

80

75

70

65

60

How Sleep Affects Math Scores

5b. positive; Sample answer: As the sleep

increases, the math test score increases.

5c. Sample answer: 65

77 a. The two sets of data show a positive

relationship. As the years increase, so do the

number of voters. 7b. Use a straightedge to make

a line that comes close to all of the points. Look

across to the vertical axis where the line is above

the year 2011, halfway from 2010 to 2012. It looks

as though it would be about $56,000.

11. mode; Sample answer: The other three are ways
    to display data. 13. A


12. about $75

Monthly Heating Cost

Jan Mar May Jul Sept Nov

75

50

25

100

125

150

Cost ($)

Month

0

17. median: 81; UQ: 89.5; LQ: 71; IQR: 18.5
    Pages 542–545 Lesson 9-4C


18. line graph; compares values over a length of time


19. circle graph; compares parts to a whole
    55 A histogram would be appropriate because it
    shows data divided into equal intervals. To construct
    a histogram of this data, use the intervals $2.00–$2.99,
    $3.00–$3.99, $4.00–$4.99, and $5.00–$5.99. Put these
    intervals on the horizontal axis. On the vertical
    axis, show the scale 0 to 3. Be sure to label the axis
    and title the graph.
    Sandwich Prices

5.00–

5.99

4.00–

4.99

3.00–

3.99

2.00–

2.99

2

3

1

0

1.5

2.5

0.5

3.5

Number of Sandwiches

Price ($)

Sample answer: Most sandwiches cost between

$3.00–$4.99.

77 A box-and-whisker plot would be the most

appropriate display because it shows the median

along with other measures of variation.

9. circle graph; compares parts to whole


10. scatter plot; compares two sets of data

Depth of Ice at Different

Temperatures

010203040

3

4

5

2

1

6

Depth of Ice (in.)

Temperature (°F)

0

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