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Answers to Quiz #1 for Econ 10a
1.
The nominal scale of measurement has the properties of the
a. ordinal scale
b. only interval
scale
c. ratio scale
d.
None of the above answers is correct.
Answer: d
2.
Income is an example of a variable that uses the
a. ratio scale
b. interval
scale
c. nominal scale
d.
ordinal scale
Answer: a
3.
Data
a. are always be
numeric
b. are always
nonnumeric
c. are the raw
material of statistics
d.
None of the above answers is correct.
Answer: c
4.
The number of cases will always be the same as the number of
a. variables
b. elements
c. data sets
d.
data
Answer: b
5.
Social security numbers consist of numeric values.
Therefore, social security is an example of
a. a
quantitative variable
b. either a
quantitative or a qualitative variable
c. an exchange
variable
d.
a qualitative variable
Answer: d
6.
The summaries of data, which may be tabular, graphical, or
numerical, are referred to as
a. inferential
statistics
b. descriptive
statistics
c. statistical
inference
d.
report generation
Answer: b
7.
The collection of all elements of interest in a particular study
is
a. the
population
b. the sampling
c. statistical
inference
d.
descriptive statistics
Answer: a
8.
A statistics professor asked students in a class their ages.
On the basis of this information, the professor states that the
average age of all the students in the university is 24 years.
This is an example of
a. a census
b. descriptive
statistics
c. an experiment
d.
statistical inference
Answer: d
9.
If several frequency distributions are constructed from the same
data set, the distribution with the widest class width will have the
a. fewest
classes
b. most classes
c.
same number of classes as the other distributions since all are
constructed from the same data
Answer:
a
10.
The total number of data items with a value less than the upper
limit for the class is given by the
a. frequency
distribution
b. relative
frequency distribution
c. cumulative
frequency distribution
d.
cumulative relative frequency distribution
Answer:
c
A survey of 800 college seniors resulted in the following
crosstabulation regarding their undergraduate major and whether or not
they plan to go to graduate school. (Exhibit 2-2)
|
Undergraduate Major
|
|
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Graduate
School
|
Business
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Engineering
|
Others
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Total
|
|
Yes
|
70
|
84
|
126
|
280
|
|
No
|
182
|
208
|
130
|
520
|
|
Total
|
252
|
292
|
256
|
800
|
|
|
|
|
|
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11.
Refer to Exhibit 2-2. What
percentage of the students' undergraduate major is engineering?
a. 292
b. 520
c. 65
d. 36.5
Answer: d
12.
Refer to Exhibit 2-2. Of
those students who are majoring in business, what percentage plans to go
to graduate school?
a. 27.78
b. 8.75
c. 70
d.
72.22
Answer: a
13.
The frequency distribution below was constructed from data
collected on the quarts of soft drinks consumed per week by 20 students.
Quarts of Soft Drink
Frequency
0 - 3
4
4 - 7
5
8 - 11
6
12 - 15
3
16 - 19
2
a. Construct a
relative frequency distribution.
b. Construct a
cumulative frequency distribution.
c. Construct a
cumulative relative frequency distribution.
Answers:
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a.
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b.
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c.
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Cumulative
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Quarts
of
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Relative
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Cumulative
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Relative
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Soft
Drinks
|
Frequency
|
Frequency
|
Frequency
|
Frequency
|
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0
– 4
|
4
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0.20
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4
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0.20
|
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4 -
8
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5
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0.25
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9
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0.45
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8
– 12
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6
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0.30
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15
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0.75
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12
– 16
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3
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0.15
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18
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0.90
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16
– 20
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2
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0.10
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20
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1.00
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Total
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20
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1.00
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14.
The SAT scores of a sample of business school students and their
genders are shown below.
SAT Scores
|
|
|
Gender
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Less than 20
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20 up to 25
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25 and more
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Total
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Female
|
24
|
168
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48
|
240
|
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Male
|
40
|
96
|
24
|
160
|
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Total
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64
|
264
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72
|
400
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a. How many
students scored less than 20?
b. How many
students were female?
c. Of the male
students, how many scored 25 or more?
d. Compute row
percentages and comment on any relationship that may exist between SAT
scores and gender of the individuals.
e. Compute
column percentages.
Answers:
a. 64
b. 240
c. 24
d.
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SAT
Scores
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Gender
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Less than 20
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20 up to 25
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25 and more
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Total
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Female
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10%
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70%
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20%
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100%
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Male
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25%
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60%
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15%
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100%
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From the above percentages it can be noted that the largest
percentages of both genders' SAT scores are in the 20 to 25 range.
However, 70% of females and only 60% of males have SAT scores in
this range. Also it can be
noted that 10% of females' SAT scores are under 20, whereas, 25% of
males' SAT scores fall in this category.
e.
|
SAT
Scores
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|
|
Gender
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Less than 20
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20 up to 25
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25 and more
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Female
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37.5%
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63.6%
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66.7%
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Male
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62.5%
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36.4%
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33.3%
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Total
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100%
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100%
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100%
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15. For the following observations and its scatter diagram,
please indicate what kind of relationship (if any) exist between x and
y.
x y
2
7
6
19
3
9
5
17
4
11
a
positive relationship
16.
The sum of the relative frequencies for all classes will always
equal
a. the sample
size
b. the number of
classes
c. one
d.
any value larger than one
Answer:
c
17. The mean of a sample
a.
is always equal to the mean of the population
b.
is always smaller than the mean of the population
c.
is computed by summing the data values and dividing the sum by (n
- 1)
d.
is computed by summing all the data values and dividing the sum
by the number of items
Answer:
d
18. The median of a sample will
always equal the
a.
mode
b.
mean
c.
50th percentile
d.
all of the above answers are correct
Answer:
c
A researcher has collected the following sample
data (Exhibit 3-2)
5
12
6
8
5
6
7
5
12
4
19a. Refer to Exhibit 3-2.
The median is
a.
5
b.
6
c.
7
d.
8
Answer:
b
19b. Refer to Exhibit 3-2.
The mode is
a.
5
b.
6
c.
7
d.
8
Answer:
a
20. The numerical value of the
standard deviation can never be
a.
larger than the variance
b.
zero
c.
negative
d.
smaller than the variance
Answer:
c
21. If two groups of numbers have the
same mean, then
a.
their standard deviations must also be equal
b.
their medians must also be equal
c.
their modes must also be equal
d.
None of these alternatives is correct
Answer:
d
22. Positive values of covariance
indicate
a.
a positive variance of the x values
b.
a positive variance of the y values
c.
the standard deviation is positive
d.
positive relation between the independent and the dependent
variables
Answer:
d
23.
Given the following information:
Standard deviation = 8
Coefficient of variation = 64%
The mean would then be
a. 12.5
b. 8
c. 0.64
d.
1.25
Answer: a
24.
A high school guidance counselor collected the following data
about GPA and SAT math scores for six students:
GPA 2.7
3.5 3.7
3.3 3.6
3.0
SAT 450 560 700 620 640 570
Compute
the sample correlation coefficient. What does this value tell us about
the relationship between GPA and SAT?
Answer: 0.871, positively linearly related.
25.
Consider the sample data in the following frequency table
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Class
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Midpoint
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Frequency
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3-7
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5
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12
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8-12
|
10
|
5
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13-17
|
15
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2
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18-22
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20
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1
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Compute the sample mean and sample standard deviation.
Answer: 8, 4.41
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