Practice Exam 1
1. Data may be classified by one of the four levels of measurement. Which is the lowest level?
A. ordinal
B. nominal
C. ratio
D. population
E. interval
2. Which level of measurement is suitable for putting data into categories?
A. ratio
B. interval
C. ordinal
D. inferential
E. nominal
3. A professor of social science at a certain university questioned 200 students out of a total enrollment of 12,243 concerning their
opinions of the quality of various university services. Identify the variable.
A. the professor
B. 200 students
C. the students’ opinions
D. the total enrollment
E. social science
4. English 105: Great Writers of America has 447 students. To estimate the amount of time students in this section spent studying
for the midterm exam a random sample of 40 students were surveyed.
A. What is the population?
B. What is the sample?
5. A random-number table is to be used to pick a random sample of 40 sheep out of a population of 300 sheep. If the blocks of five
digits need to be regrouped, how many digits should be included in each block?
A. 5
B. 4
C. 3
D. 2
E. 1
6. To determine monthly rental prices of apartment units in the San Francisco Bay area, samples were constructed in the following
always. Identify the technique used to produce each sample. (cluster, convenience, simple random, stratified, systematic)
(a) Number all the units in the area and use a random number table to select the apartments to include in
the sample.
(b) Classify the apartment units according to the number of bedrooms and then take a random sample
from each of the classes.
(c) Classify the apartments according to zip code and take a random sample from each of the zip code
regions.
(d) Look in the newspaper and choose the first apartments you find that list rents.
7. Some people are attracted to those who are like them. Others are attracted to those who are quite different. In a study of this
phenomenon a random sample of 32 people were surveyed to determine their rating of attraction to people quite different from
themselves. A scale from 1 to 20 was used. 20 represents feelings of greatest attraction. The results follow.
2
12
16
17
3
15
9
16
10
8
5
11
3
2
1
6
7
8
10
4
5
15
17
6
3
7
16
6
19
15
2
14
(a) Make a frequency table for this data using 5 classes.
(b) Draw a histogram.
8. The first year students on one floor of a dorm were polled to determine how often they phoned home
during the first 8 weeks of the fall term. The results are given below.
5
9
12
8
2
6
6
12
6
25
28
12
4
14
10
21
17
20
10
12
9
1
1
6
24
16
8
12
18
6
4
18
8
16
3
15
Make a stem and leaf display of the data using the tens digit for the stem and using 2 lines per stem.
9. The Statistical Abstract of the United States (117th edition) reports the number of families below the
poverty level by age of householder. There are a total of 7,509,000 such families. The table below
shows the breakdown by age of householder. Use the frequency table to answer the questions below.
Age Interval
Percent
15- < 25
13.2
25- < 35
30.4
35 - < 45
26.1
45 - < 55
12.6
55 - < 65
9.4
65 and older
8.2
(a) What is the class width?
(b) Describe the shape of the histogram.
(c) Which age category has the highest percentage of families below the poverty level?
(d) What percentage of families below the poverty level have householders 34 years of age or younger?
10. The public relations and advertising office of the Allstart Battery Company wants information about the life of their car
batteries. When a customer buys an Allstart battery he or she sends a guarantee certificate to the public relations office. A
random sample of 42 customers was traced by means of return addresses on the guarantee certificates. Battery lives for the
batteries purchased by these customers are given below (recorded to the nearest month).
13
25
33
45
14
26
34
46
18
26
34
48
19
26
34
49
21
27
34
50
21
28
35
56
22
29
36
23
29
38
23
30
39
72
69
81
66
64
65
Use a class width of 6 to make a frequency table.
11. Find the mean of the following ages of retirees:
79
68
75
71
83
66
91
86
66
64
68
80
24
31
40
24
32
41
25
33
41
A. 66
B. 68.5
C. 72
D. 73
E. 70
12. Find the mode of the following set of numbers:
1
4
3
2
A. 2.5
2
1
3
B. 4
3
4
C. no mode
1
2
D. 3
4
4
1
2
3
E. 2
13. Calculate a 5% trimmed mean for the following set of ages (in years) of giant tortoises:
5
29
12
20
16
36
24
3
33
17
7
81
9
50
13
22
42
62
21
41
14. The resting heart-rates for 10 members of a school’s soccer team were measured by the school nurse. The results were the
following (beats per minute):
55
58
57
62
64
61
56
60
63
65
Compute the sample mean, sample standard deviation, and the coefficient of variation. Round to the nearest hundredth if necessary.
A. x = 60.0
s = 3.48
CV = 5.78%
B. x = 60.1
s = 3.48
CV = 5.79%
C. x = 60.0
s = 3.47
CV = 5.78%
D. x = 60.1
s = 3.47
CV = 5.79%
E. x = 60.0
s = 3.48
CV = 5.78%
15. A supermarket sells eight brands of 8-oz cans of baked beans, with the following prices (dollars per can):
0.98
1.29
1.59
1.69
1.09
1.49
1.19
1.38
Compute the population mean and population standard deviation.
A. µ = $1.34

= $0.23
B. µ = $1.34

= $0.25
C. µ = $1.33

= $0.23
D. µ = $1.33

= $0.22
E. µ = $1.32

= $0.24
16. The Richter scale is used to measure the magnitude of earthquakes. The scale readings are such that 1 represents an earthquake
that is observed only on instruments, while 3 indicates a quake felt only by people near its epicenter. A reading of 7 represents a
major quake, usually accompanied by substantial destruction. A sample of 15 earthquakes occurring in the United States had
readings on the Richter scale of
1.0
2.0
2.1
3.1
1.3
4.6
5.1
1.2
3.4
1.8
2.1
2.7
1.4
3.5
1.5
A. Compute the five-number summary and the interquartile range.
B. Make a box-and-whisker plot.
17. The Softex Plastic Company tested a random sample of 12 pieces of new plastic for breaking strength. They obtained the
following measurements in units of 1,000 pounds per square inch:
2.0
2.3
4.1
3.3
1.9
3.5
3.4
1.8
4.0
2.7
2.6
3.9
(a) Compute the five-number summary and the interquartile range.
(b) Make a box-and-whisker plot.
(c) Find the range.
(d) Find the mean.
(e) Find the sample standard deviation.
18. The number of hours of volunteer service given last month by nurses at the Red Cross emergency station were as follows:
10
6
Find
8
3
13
8
5
9
A.) the mean,
6
8
8
2
15
4
B.) the median and
8
16
7
11
C.) the mode
3
12
of the hours of volunteer service.
19. Consider the following set of data:
1.2
6.1
0.7
3.6
7.3
1.9
Find
5.1
9.5
4.6
A).
4.8
2.4
2.1
Q3
10.2
11.1
9.8
and
B.)
the interquartile range.
20. Compute the 10% trimmed mean for the following set of data:
1.1
5.6
8.9
18.2
19.1
7.2
8.2
7.4
6.9
15.5
3.6
4.7
11.8
12.4
17.7
2.5
10.3
8.7
7.1
6.4
A.) 8.8
B.) 8.9
C.) 9.0
D.) 9.1
E.) 9.2
4
7