商务统计学笔试复习题

一、The manager of the customer service division of a major consumer electronics company is interested in determining whether the customers who have purchased a videocassette recorder made by the company over the past 12 months are satisfied with their products.

1., the population of interest is

a)all the customers who have bought a videocassette recorder made

by the company over the past 12 months.

b)all the customers who have bought a videocassette recorder made

by the company and brought it in for repair over the past 12 months.

c)all the customers who have used a videocassette recorder over the

past 12 months.

d)all the customers who have ever bought a videocassette recorder

made by the company.

ANSWER:

a

2., which of the following will be a good frame for drawing a sample?

a)Telephone directory.

b)Voting registry.

c)The list of customers who returned the registration card.

d) A list of potential customers purchased from a database marketing

company.

ANSWER:

c

3.the possible responses to the question "How many videocassette recorders

made by other manufacturers have you used?" are values from a

a)discrete random variable.

b)continuous random variable.

c)categorical random variable.

d)parameter.

ANSWER:

a

4. the possible responses to the question "Are you happy, indifferent, or

unhappy with the performance per dollar spent on the videocassette recorder?" are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER:

c

TYPE: MC DIFFICULTY: Easy

KEYWORDS: categorical random variable, types of data

5.the possible responses to the question "What is your annual income rounded

to the nearest thousands?" are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER:

a

6.the possible responses to the question "How much time do you use the

videocassette recorder every week on the average?" are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER:b

7.the possible responses to the question "How many people are there in your

household?" are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER:a

8.the possible responses to the question "How would you rate the quality

of your purchase experience with 1 = excellent, 2 = good, 3 = decent,

4 = poor,

5 = terrible?" are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER: c

9.the possible responses to the question "What brand of videocassette

recorder did you purchase?" are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER:c

10.the possible responses to the question "Out of a 100 point score with

100 being the highest and 0 being the lowest, what is your satisfaction level on the videocassette recorder that you purchased?" are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER:a

11.the possible responses to the question "In which year were you born?"

are values from a

a)discrete numerical random variable.

b)continuous numerical random variable.

c)categorical random variable.

d)parameter.

ANSWER:a

二、The chancellor of a major university was concerned about alcohol abuse on her campus and wanted to find out the proportion of students at her university who visited campus bars on the weekend before the final exam week. Her assistant took a random sample of 250 students. The total number of students in the sample who visited campus bars on the weekend before the final exam week is an example of

e) a categorical random variable.

f) a discrete random variable.

g) a continuous random variable.

h) a parameter.

ANSWER:

b

三、T he chancellor of a major university was concerned about alcohol abuse on

her campus and wanted to find out the proportion of students at her

university who visited campus bars on the weekend before the final exam week.

Her assistant took a random sample of 250 students and computed the portion of students in the sample who visited campus bars on the weekend before the final exam. The portion of all students at her university who visited campus bars on the weekend before the final exam week is an example of

i) a categorical random variable.

j) a discrete random variable.

k) a continuous random variable.

l) a parameter.

ANSWER:

d

四、T he chancellor of a major university was concerned about alcohol abuse on

her campus and wanted to find out the proportion of students at her

university who visited campus bars on the weekend before the final exam week.

Her assistant took a random sample of 250 students. The portion of students in the sample who visited campus bars on the weekend before the final exam week is an example of __________.

m)a categorical random variable.

n) a discrete random variable.

o) a parameter.

p) a statistic

ANSWER:

d

五、The ordered array below resulted from taking a sample of 25 batches of 500 computer chips and determining how many in each batch were defective.

Defects

1 2 4 4 5 5 6 7 9 9 12 12 15

17 20 21 23 23 25 26 27 27 28 29 29

1.Referring to Table 2-11, if a frequency distribution for the defects data

is constructed, using "0 but less than 5" as the first class, the frequency of the “20 but less than 25” class would be ________.

ANSWER:

4

2.Referring to Table 2-11, if a frequency distribution for the defects data

is constructed, using "0 but less than 5" as the first class, the relative frequency of the “15 but less than 20” class would be ________.

ANSWER:

0.08 or 8% or 2/25

3.Referring to Table 2-11, construct a frequency distribution for the

defects data, using "0 but less than 5" as the first class.

ANSWER:

Defects Frequency

0 but less than 5 4

5 but less than 10 6

10 but less than 15 2

15 but less than 20 2

20 but less than 25 4

25 but less than 30 7

4.Referring to Table 2-11, construct a relative frequency or percentage

distribution for the defects data, using "0 but less than 5" as the first class.

ANSWER:

Defects Percentage

0 but less than 5 16

5 but less than 10 24

10 but less than 15 8

15 but less than 20 8

20 but less than 25 16

25 but less than 30 28

5.Referring to Table 2-11, construct a cumulative percentage distribution

for the defects data if the corresponding frequency distribution uses "0 but less than 5" as the first class.

ANSWER:

Defects CumPct

0 0

5 16

10 40

15 48

20 56

25 72

30 100

6.Referring to Table 2-11, construct a histogram for the defects data, using

"0 but less than 5" as the first class.

ANSWER:

7. Referring to Table 2-11, construct a cumulative percentage polygon for

the defects data if the corresponding frequency distribution uses "0 but less than 5" as the first class.

ANSWER:

Cumulative Percentage Polygon

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0510********

Number of Defects

六、Health care issues are receiving much attention in both academic and political arenas. A sociologist recently conducted a survey of citizens over 60 years of age whose net worth is too high to qualify for Medicaid and have no private health insurance. The ages of 25 uninsured senior citizens were as follows:

60 61 62 63 64 65 66 68 68 69 70 73 73

74 75 76 76 81 81 82 86 87 89 90 92

1. Referring to Table 3-1, calculate the arithmetic mean age of the uninsured

senior citizens to the nearest hundredth of a year.

ANSWER:

74.04 years

2.Referring to Table 3-1, identify the median age of the uninsured senior

citizens.

ANSWER:

73 years

3.Referring to Table 3-1, identify the first quartile of the ages of the

uninsured senior citizens.

ANSWER:

65.5 years

4.Referring to Table 3-1, identify the third quartile of the ages of the

uninsured senior citizens.

ANSWER:

81.5 years

5.Referring to Table 3-1, identify the interquartile range of the ages of

the uninsured senior citizens.

ANSWER:

16 years

6.Referring to Table 3-1, identify which of the following is the correct

statement.

a)One fourth of the senior citizens sampled are below 65.5 years of

age.

b)The middle 50% of the senior citizens sampled are between 65.5 and

73.0 years of age.

c)The average age of senior citizens sampled is 73.5 years of age.

d)All of the above are correct.

ANSWER:

a

7.Referring to Table 3-1, identify which of the following is the correct

statement.

a)One fourth of the senior citizens sampled are below 64 years of

age.

b)The middle 50% of the senior citizens sampled are between 65.5 and

73.0 years of age.

c)25% of the senior citizens sampled are older than 81.5 years of

age.

d)All of the above are correct.

ANSWER:

c

8.Referring to Table 3-1, what type of shape does the distribution of the

sample appear to have?

ANSWER:

Slightly positive or right-skewed.

9.Referring to Table 3-1, calculate the variance of the ages of the

uninsured senior citizens correct to the nearest hundredth of a year squared.

ANSWER:

94.96 years2

10.Referring to Table 3-1, calculate the standard deviation of the ages of

the uninsured senior citizens correct to the nearest hundredth of a year.

ANSWER:

9.74 years

11.Referring to Table 3-1, calculate the coefficient of variation of the

ages of the uninsured senior citizens.

ANSWER:

13.16%

七、The stem-and-leaf display below represents the number of cargo manifests approved by customs inspectors of the Port of New York in a sample of 35 days.

STEM LEAVES

1H 67889

2L 0011122223333444

2H 5566678899

3L 1122

Note (1): 1H means the “high teens” 15, 16, 17, 18, or 19; 2L means the “low twenties” 20, 21, 22, 23, or 24; 2H means the “high twenties” 25, 26, 27, 28, or 29, etc.

Note (2): For this sample, the sum of the observations is 838, the sum of the squares of the observations is 20,684, and the sum of the squared differences between each observation and the mean is 619.89.

1.Referring to Table 3-4, the arithmetic mean of the customs data is

________.

ANSWER:

23.9

2.Referring to Table 3-4, the median of the customs data is ________.

ANSWER:

23

3.Referring to Table 3-4, the first quartile of the customs data is

________.

ANSWER:

21

4.Referring to Table 3-4, the third quartile of the customs data is

________.

ANSWER:

27

5.Referring to Table 3-4, the range of the customs data is ________.

ANSWER:

16

6.Referring to Table 3-4, the interquartile range of the customs data is

________.

ANSWER:

6

7.Referring to Table 3-4, the variance of the customs data is ________.

ANSWER:

18.2

8.Referring to Table 3-4, the standard deviation of the customs data is

________.

ANSWER:

4.3

9.Referring to Table 3-4, the coefficient of variation of the customs data

is ________ percent.

ANSWER:

17.8% or 18%

10.Referring to Table 3-4, the five-number summary for the data in the

customs sample consists of ________, ________, ________, ________,

________.

ANSWER:

16, 21, 23, 27, 32

11.Referring to Table 3-4, construct a boxplot of this sample.

Box-and-whisker Plot

101520253035

ANSWER:

八、Times spent studying by students in the week before final exams follow a normal distribution with standard deviation 8 hours. A random sample of 4 students was taken in order to estimate the mean study time for the population of all students.

1.what is the probability that the sample mean exceeds the population mean

by more than 2 hours?

ANSWER:

0.3085

2. what is the probability that the sample mean is more than 3 hours below

the population mean?