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Chapter 2: Q129E (page 131)

Question: Hourly road accidents in India.An analysis of road accident data in India was undertaken, and the results were published in the Journal of Big Data(Vol. 2, 2015). For a particular cluster of roads, the hourly numbers of accidents totaled over a recent 5-year period are listed in the next table. (These results are adapted from a figure in the journal article.) Create a scatterplot of the data, with a number of accidents on the vertical axis and hours on the horizontal axis. What type of trend (if any) do you detect in the data?

Hour

Number

1

2

3

4

5

6

7

8

9

10

11

12

125

148

159

270

281

295

302

216

225

353

400

327

Short Answer

Expert verified

Answer:

The graph is given below:

There is a positive trend.

Step by step solution

01

Creating the scatter plot

We will plot the number of accidents on the y-axis and the hour on the x-axis.

The graph is given below:

02

Identifying the trend

We notice that as hours increase, the number of accidents also increases.Therefore, there is a positive correlation between the number of accidents and hours.

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Most popular questions from this chapter

Question: Permeability of sandstone during weathering.Refer to the Geographical Analysis(Vol. 42, 2010) study of the decay properties of sandstone when exposed to the weather, Exercise 2.47 (p. 96). Recall that slices of sandstone blocks were tested for permeability under three conditions: no exposure to any type of weathering (A), repeatedly sprayed with a 10% salt solution (B), and soaked in a 10% salt solution and dried (C). Measures of variation for the permeability measurements (mV) of each sandstone group are displayed in the accompanying Minitab printout.

Descriptive Statistics: PermA, PermB, PermC

Variable

N

StDev.

Variance

Minimum

Maximum

Range

PermA

100

14.48

209.53

55.20

122.40

67.20

PermB

100

21.97

482.75

50.40

150.00

99.60

PermC

100

20.05

401.94

52.20

129.00

76.80

a.Find the range of the permeability measurements for Group A sandstone slices. Verify its value using the minimum and maximum values shown on the printout.

b.Find the standard deviation of the permeability measurements for Group A sandstone slices. Verify its value using the variance shown on the printout.

c.Which condition (A, B, or C) has the more variable permeability data?

Question: Lobster trap placement.The strategic placement of lobster traps is one of the keys to a successful lobster fisherman. An observational study of teams fishing for the red spiny lobster in Baja California Sur, Mexico, was conducted and the results were published in the Bulletin of Marine Science(April 2010). Two variables measured for each of eightteams from the Punta Abreojos (PA) fishing cooperativewere y= total catch of lobsters (in kilograms) during theseason and x= average percentage of traps allocated perday to exploring areas of unknown catch (called search frequency).These data are listed in the next table. Graph

the data in a scatterplot. What type of trend, if any, do you observe?

Total Catch

Search Frequency

2785

35

6535

21

6695

26

4891

29

4937

23

5727

17

7019

21

5735

20

Refer to Exercise 2.141. Assuming all populations are approximately mound-shaped, for parts a–d, determine whether the values 0, 4, and 12 are outliers.

Motivation of drug dealers.Consider a study of drug dealers and their motivation for participating in the illegal drug market (Applied Psychology in Criminal Justice, September 2009). The sample consisted of 100 convicted drug dealers who attended a court-mandated counseling program. Each dealer was scored on the Wanting Recognition (WR) Scale, which provides a quantitative measure of a person’s level of need for approval and sensitivity to social situations. (Higher scores indicate a greater need for approval.) The sample of drug dealers had a mean WR score of 39, with a standard deviation of 6. Assume the distribution of WR scores for drug dealers is mound-shaped and symmetric.

a.Give a range of WR scores that will contain about 95% of the scores in the drug dealer sample.

b.What proportion of the drug dealers had WR scores above 51?

c.Give a range of WR sores that contain nearly all the scores in the drug dealer sample.

Defects in new automobiles.Consider the following data from the automobile industry. All cars produced on a particular day were inspected for defects. The 145 defects found were categorized by type as shown in the accompanying table.

Defect Type

Number

Accessories

Body

Electrical

Engine

Transmission

50

70

10

5

10

a.Construct a Pareto diagram for the data. Use the graph to identify the most frequently observed type of defect.

b.All 70 car body defects were further classified as to type. The frequencies are provided in the following table. Form a Pareto diagram for the type of body defect. (Adding this graph to the original Pareto diagram of part a is called exploding the Pareto diagram.) Interpret the result. What type of body defect should be targeted for special attention?

Body Defect

Number

Chrome

Dents

Paint

Upholstery

Windshield

2

25

30

10

3
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