Unordered stem and leaf plot

4. The number of service calls made by Zappos’ customer service team over the past 30 days is shown in the table:

35

48

31

36

41

33

55

61

52

29

43

47

36

46

47

52

45

32

50

55

41

25

36

61

53

59

37

60

68

27

a. Determine and interpret the 35th percentile value for the service call data.

b. Determine and interpret the 60th percentile value.

c. Determine and interpret the median value. d. What is the percentile for 43 service calls?

9. 9. Last year’s percentage increase in value for each of the 15 stocks in your investment portfolio is given below. Determine Q1, Q2, and Q3.

Percentage Increase

1.1

3.2

6.8

5.5

3.6

8.9

4.5

6.0

7.8

12.1

5.2

15.7

2.5

6.2

5.4

17. Determine and interpret the interquartile range for the data in Exercise 8 showing months of useful cell phone life. The unordered list is reproduced below: 12.7, 23.5, 26.8, 15.5, 13.6, 28.9, 14.5, 36.0, 27.8, 25.2, 35.7, 62.5, 16.2, 35.5, 28.2, 15.6, 32.7, 22.1

24. The data below show the number of cases of pneumonia reported in the state of Maryland during the last 15 months.

AUG

SEP

OCT

NOV

DEC

219

181

173

188

207

JAN

FEB

MAR

APR

MAY

205

179

212

215

174

JUN

JUL

AUG

SEP

OCT

218

194

203

215

191

a. Create a stem-and-leaf diagram to display the data using two leading digits to form the stem. Retain the original order when entering the leaf values.

b. Produce an ordered stem-and-leaf diagram by putting the leaf values in ascending order.

34. The data from Exercise 9 are reproduced in the table below. The table shows last year’s percentage increase in value for each of the 15 stocks in your investment portfolio:

EXERCISES

1.1

3.2

6.8

5.5

3.6

8.9

4.5

6.0

7.8

12.1

5.2

15.7

2.5

6.2

5.4

Draw the box plot

44. Below is the table from Exercise 2 showing the number of flights at US airports that were delayed on the tarmac for more than three hours before departure during a recent 12-month period (source: Department of Transportation Statistics.

Month

Delayed Flights

March

85

1

4

April

74

2

6

May

34

3

11

June

268

4

20

July

161

5

34

August

66

6

34

September

6

7

60

October

11

8

66

November

4

9

74

December

34

10

85

January

20

11

161

February

60

12

268

a. Show the box plot and use the “1.5 x interquartile range” approach to identify any outliers.

Q1

b. Use the “3-standard-deviation” approach to identify any outliers. (The standard deviation of the delay data is 73.5 flights.)

c. Calculate the z-score for the value 268.

47. The number of vacationers visiting Hawaii during a four-year period is shown in the table below. Also shown is the estimated number of visitors to Walt Disney’s Magic Kingdom over the same period. Show the scatter diagram. Compute the covariance and interpret the result2010 6.9 15.4 2011 6.3 14.7 2012 7.1 16.1 2013 7.4 16.5

Year

Hawaii Visitors (millions)

Magic Kingdom Visitors (millions)

2010

6.9

15.4

2011

6.3

14.7

2012

7.1

16.1

2013

7.4

16.5

69. The Wall Street Journal reported that the Chinese government is planning to adopt more stringent automobile fuel efficiency standards to keep oil consumption in check (source: WSJ.com). The standards vary depending on the type of vehicle. An SUV is required to get 17 mpg (miles per gallon). Medium weight passenger cars are required to get 25 mpg, and lighter passenger cars are required to get 33 mpg. If Ford Motors-China last year sold 138,000 SUVs, 291,000 medium weight passenger cars, and 482,000 light passenger cars in China, and all met precisely the fuel efficiency standards described, what was the average mileage for