CHAPTER EIGHT
Statistical Inference: Estimation for Single Populations
B
1.
M
Term
A
E
Term
When a statistic calculated from sample data is used to estimate a population
parameter, it is called _______.
A.
B.
C.
D.
2.
an interval estimate
a point estimate
a statistical parameter
a good guess
When a range of values is used to estimate a population parameter, it is called
_______.
A.
B.
C.
D.
an interval estimate
a point estimate
a statistical parameter
a range estimate
233
234
Test Bank
A
3.
M
BApp
D
A.
B.
C.
D.
4.
M
BApp
C
M
BApp
Catherine Chao, Director of Marketing Research, is evaluating consumer
acceptance of a new toothpaste package. Her staff reports that 17% of a random
sample of 200 households prefer the new package to all other package designs. If
Catherine concludes that 17% of all households prefer the new package, she is
using a _______.
Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service
level provided to walk-in customers. Accordingly, his staff recorded the waiting
times for 45 randomly selected walk-in customers, and calculated that their mean
waiting time was 15 minutes. If Brian concludes that the average waiting time
for all walk-in customers is 15 minutes, he is using a ________.
A.
B.
C.
D.
5.
a point estimate
a range estimate
a statistical parameter
an interval estimate
a range estimate
a statistical parameter
an interval estimate
a point estimate
Eugene Gates, Marketing Director of Mansfield Motors Manufacturers, Inc.’s
Electrical Division, is leading a study to assess the relative importance of product
features. An item on a survey questionnaire distributed to 100 of Mansfield’s
customers asked them to rate the importance of “ease of maintenance” on a scale
of 1 to 10 (with 1 meaning “not important” and 10 meaning “highly important”).
His staff assembled the following statistics.
Ease of Maintenance
Mean
7.5
Standard Deviation
1.5
If Eugene concludes that the average rate of “ease of maintenance” for all
customers is 7.5, he is using ________.
A.
B.
C.
D.
arange estimate
a statistical parameter
a point estimate
an interval estimate
Chapter 8: Statistical Inference: Estimation for Single Populations 235
A
6.
M
BApp
D
M
BApp
Eugene Gates, Marketing Director of Mansfield Motors Manufacturers, Inc.’s
Electrical Division, is leading a study to assess the relative importance of product
features. An item on a survey questionnaire distributed to 100 of Mansfield’s
customers asked them to rate the importance of “efficiency of operation” on a
scale of 1 to 10 (with 1 meaning “not important” and 10 meaning “highly
important”). His staff assembled the following statistics.
Efficiency of Operation
Mean
6.0
Standard Deviation
2.5
If Eugene concludes that the average rate of “efficiency of operation” for all
customers is 6.0, he is using ________.
A.
B.
C.
D.
7.
a point estimate
a statistical parameter
a range estimate
an interval estimate
Mary Flindt, a Marketing Director with Epsilon Airlines, is assessing the relative
importance of the "total flight" experience. An item on a survey questionnaire
distributed to 100 of Epsilon's customers asked them to rate the importance of
“on-time arrival” on a scale of 1 to 10 (with 1 meaning “not important” and 10
meaning “highly important”). Her staff assembled the following statistics from
the responses.
On-time Arrival
Mean
9.1
Standard Deviation
2.5
If Mary concludes that the average rate of “on-time arrival” for all customers is
9.1, she is using ________.
A.
B.
C.
D.
an interval estimate
a statistical parameter
a range estimate
a point estimate
236
Test Bank
D
8.
M
BApp
B
A.
B.
C.
D.
9.
E
Calc
C
10.
E
Calc
1.28
1.645
1.96
2.575
The Z value associated with a two-sided 95% confidence interval is _______.
A.
B.
C.
D.
11.
an interval estimate
a statistical parameter
a range estimate
a point estimate
The Z value associated with a two-sided 90% confidence interval is _______.
A.
B.
C.
D.
E
Calc
B
Mary Flindt, a Marketing Director with Epsilon Airlines, is assessing the relative
importance of the "total flight" experience. An item on a survey questionnaire
distributed to 100 of Epsilon's customers asked them to rate the importance of
“cabin space” on a scale of 1 to 10 (with 1 meaning “not important” and 10
meaning “highly important”). Her staff assembled the following statistics from
the responses.
Cabin Space
Mean
7.2
Standard Deviation
3.7
If Mary concludes that the average rate of “cabin space” for all customers is 7.2,
she is using ________.
1.28
1.645
1.96
2.575
The Z value associated with a two-sided 80% confidence interval is _______.
A.
B.
C.
D.
1.645
1.28
0.84
0.29
Chapter 8: Statistical Inference: Estimation for Single Populations 237
B
12.
E
Calc
D
A.
B.
C.
D.
13.
E
Calc
B
14.
M
Calc
A
M
Calc
1.41
1.34
0.46
1.75
Suppose a random sample of 36 is selected from a population with a standard
deviation of 12. If the sample mean is 98, the 99% confidence interval to estimate
the population mean is _______.
A.
B.
C.
D.
16.
1.41
0.92
0.46
1.75
The Z value associated with a two-sided 82% confidence interval is _______.
A.
B.
C.
D.
15.
1.28
1.55
1.17
0.88
The Z value associated with a two-sided 92% confidence interval is _______.
A.
B.
C.
D.
E
Calc
D
The Z value associated with a two-sided 88% confidence interval is _______.
94.08 to 101.92
92.85 to 103.15
97.35 to 98.65
93.34 to 102.66
Suppose a random sample of 36 is selected from a population with a standard
deviation of 12. If the sample mean is 98, the 90% confidence interval for the
population mean is _______.
A.
B.
C.
D.
94.71 to 101.29
97.45 to 98.55
94.08 to 101.92
97.35 to 98.65
238
Test Bank
C
17.
M
Calc
C
A.
B.
C.
D.
18.
M
Calc
B
Suppose a random sample of 36 is selected from a population with a standard
deviation of 12. If the sample mean is 98, the 95% confidence interval for the
population mean is _______.
Suppose a random sample of size 64 is selected from a population. The sample
yields a mean of 26 and a standard deviation of 4. From this information, the 90%
confidence interval to estimate the population mean can be computed to be
_______.
A.
B.
C.
D.
19.
94.71 to 101.29
97.45 to 98.55
94.08 to 101.92
97.35 to 98.65
25.36 to 26.64
25.92 to 26.08
25.18 to 26.82
25.90 to 26.10
Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service
level provided to walk-in customers. Accordingly, his staff recorded the waiting
times for 64 randomly selected walk-in customers, and determined that their mean
waiting time was 15 minutes and that the standard deviation was 4 minutes. The
90% confidence interval for the population mean of waiting times is ________.
M
BCalc
A.
B.
C.
D.
A
Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service
level provided to walk-in customers. Accordingly, his staff recorded the waiting
times for 64 randomly selected walk-in customers, and determined that their mean
waiting time was 15 minutes and that the standard deviation was 4 minutes. The
95% confidence interval for the population mean of waiting times is ________.
20.
M
BCalc
A.
B.
C.
D.
14.27 to 15.73
14.06 to 15.94
9.88 to 20.12
13.86 to 16.14
13.88 to 16.12
7.16 to 22.84
14.06 to 15.94
8.42 to 21.58
Chapter 8: Statistical Inference: Estimation for Single Populations 239
D
21.
Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service
level provided to walk-in customers. Accordingly, his staff recorded the waiting
times for 64 randomly selected walk-in customers, and determined that their mean
waiting time was 15 minutes and that the standard deviation was 4 minutes. The
88% confidence interval for the population mean of waiting times is ________.
M
BCalc
A.
B.
C.
D.
B
James Desreumaux, VP of Human Resources of American First Banks (AFB), is
reviewing the employee training programs of AFB banks. His staff randomly
selected personnel files for 100 tellers in the Southeast Region, and determined
that their mean training time was 25 hours and that the standard deviation was 5
hours. The 88% confidence interval for the population mean of training times is
________.
22.
8.80 to 21.20
14.33 to 15.67
10.30 to 19.70
14.11 to 15.89
M
BCalc
A.
B.
C.
D.
D
James Desreumaux, VP of Human Resources of American First Banks (AFB), is
reviewing the employee training programs of AFB banks. His staff randomly
selected personnel files for 100 tellers in the Southeast Region, and determined
that their mean training time was 25 hours and that the standard deviation was 5
hours. The 92% confidence interval for the population mean of training times is
________.
23.
M
BCalc
A.
B.
C.
D.
17.25 to 32.75
24.23 to 25.78
24.42 to 25.59
19.15 to 30.85
16.25 to 33.75
24.30 to 25.71
17.95 to 32.05
24.13 to 25.99
240
Test Bank
C
24.
James Desreumaux, VP of Human Resources of American First Banks (AFB), is
reviewing the employee training programs of AFB banks. His staff randomly
selected personnel files for 100 tellers in the Southeast Region, and determined
that their mean training time was 25 hours and that the standard deviation was 5
hours. The 95% confidence interval for the population mean of training times is
________.
M
BCalc
A.
B.
C.
D.
B
Eugene Gates, Marketing Director of Mansfield Motors Manufacturers, Inc.’s
Electrical Division, is leading a study to assess the relative importance of product
features. An item on a survey questionnaire distributed to 121 of Mansfield’s
customers asked them to rate the importance of “ease of maintenance” on a scale
of 1 to 10 (with 1 meaning “not important” and 10 meaning “highly important”).
His staff assembled the following statistics.
Ease of Maintenance
Mean
7.5
Standard Deviation
1.1
The 90% confidence interval for the population mean rating of “ease of
maintenance” is ________.
25.
M
BCalc
15.20 to 34.80
24.18 to 25.82
24.02 to 25.98
16.78 to 33.23
A. 5.34 to 9.66
B. 7.34 to 7.66
C. 5.69 to 9.31
D. 7.30 to 7.70
Chapter 8: Statistical Inference: Estimation for Single Populations 241
D
26.
Eugene Gates, Marketing Director of Mansfield Motors Manufacturers, Inc.’s
Electrical Division, is leading a study to assess the relative importance of product
features. An item on a survey questionnaire distributed to 121 of Mansfield’s
customers asked them to rate the importance of “ease of maintenance” on a scale
of 1 to 10 (with 1 meaning “not important” and 10 meaning “highly important”).
His staff assembled the following statistics.
Ease of Maintenance
Mean
7.5
Standard Deviation
1.1
The 95% confidence interval for the population mean rating of “ease of
maintenance” is ________.
M
BCalc
A.
B.
C.
D.
A
Mary Flindt, a Marketing Director with Epsilon Airlines, is assessing the relative
importance of the "total flight" experience. An item on a survey questionnaire
distributed to 100 of Epsilon's customers asked them to rate the importance of
“cabin space” on a scale of 1 to 10 (with 1 meaning “not important” and 10
meaning “highly important”). Her staff assembled the following statistics from
the responses.
Cabin Space
Mean
7.2
Standard Deviation
3.7
The 95% confidence interval for the population mean rating of “cabin space” is
________.
27.
M
BCalc
A.
B.
C.
D.
5.34 to 9.66
7.34 to 7.66
5.69 to 9.31
7.30 to 7.70
6.47 to 7.93
0.00 to 14.45
0.00 to 6.47
6.47 to 14.45
242
Test Bank
C
28.
Mary Flindt, a Marketing Director with Epsilon Airlines, is assessing the relative
importance of the "total flight" experience. An item on a survey questionnaire
distributed to 121 of Epsilon's customers asked them to rate the importance of
“cabin space” on a scale of 1 to 10 (with 1 meaning “not important” and 10
meaning “highly important”). Her staff assembled the following statistics from
the responses.
Cabin Space
Mean
7.2
Standard Deviation
3.7
The 99% confidence interval for the population mean rating of “cabin space” is
________.
M
BCalc
A.
B.
C.
D.
A
A random sample of 64 items is selected from a population of 400 items. The
sample mean is 200 and the sample standard deviation is 48. From this data, a
95% confidence interval to estimate the population mean can be computed as
_______.
29.
M
Calc
D
M
Calc
A.
B.
C.
D.
30.
0.00 to 7.39
0.00 to 14.45
6.33 to 8.07
6.47 to 14.45
189.21 to 210.79
188.24 to 211.76
190.13 to 209.87
190.94 to 209.06
A random sample of 64 items is selected from a population of 400 items. The
sample mean is 200 and the sample standard deviation is 48. From this data, a
90% confidence interval to estimate the population mean can be computed as
_______.
A.
B.
C.
D.
189.21 to 210.79
188.24 to 211.76
190.13 to 209.87
190.94 to 209.06
Chapter 8: Statistical Inference: Estimation for Single Populations 243
A
31.
E
Calc
C
A researcher wants to estimate the proportion of the population which possess a
given characteristic. A random sample of size 600 is taken resulting in 330 items
which possess the characteristic. The point estimate for this population proportion
is _______.
A.
B.
C.
D.
32.
0.55
0.33
0.60
0.45
The normal distribution is used to test about a population mean for large samples.
"Large" is usually defined as _______.
E
Term
A.
B.
C.
D.
B
The t test was developed by _______.
33.
at least 100
at least 5% of the population size
at least 30
at least 12
E
Term
A.
B.
C.
D.
C
The t-distribution is similar to a normal distribution. However the t-distribution is
_______.
34.
Charles Student
William Gosset
deMoivre
Gauss
M
Term
A.
B.
C.
D.
B
The t-distribution is similar to a normal distribution. However the t-distribution is
a _______.
35.
M
Term
A.
B.
C.
D.
not symmetric
bimodal
flatter
discrete
leptokurtic distribution
platykurtic distribution
mesopotamian distribution
discrete distribution
244
Test Bank
B
36.
In order to find values in the t distribution table, you must convert the sample size
or sizes to _______.
E
Term
A.
B.
C.
D.
A
If the degrees of freedom in a t distribution get very large, _______.
37.
population sizes
degrees of freedom
Z values
student values
M
Term
A.
B.
C.
D.
B
The table t value associated with the upper 5% of the t distribution and 12 degrees
of freedom is _______.
38.
E
Calc
D
A.
B.
C.
D.
39.
E
Calc
A
E
Calc
2.179
1.782
1.356
3.055
The table t value associated with the upper 5% of the t distribution and 14 degrees
of freedom is _______.
A.
B.
C.
D.
40.
the t values and the Z values are almost the same
the sample size must be very small
the population size must be very large
the sample mean approaches zero
2.977
2.624
2.145
1.761
The table t value associated with the upper 10% of the t distribution and 23
degrees of freedom is _______.
A.
B.
C.
D.
1.319
1.714
2.069
1.321
Chapter 8: Statistical Inference: Estimation for Single Populations 245
B
41.
E
Calc
A
A.
B.
C.
D.
42.
E
Calc
D
43.
E
Calc
B
E
Calc
2.947
2.602
2.131
1.753
The table t value associated with the upper 0.5% of the t distribution and 4
degrees of freedom is _______.
A.
B.
C.
D.
45.
1.333
1.337
1.740
2.567
The table t value associated with the upper 5% of the t distribution and 15 degrees
of freedom is _______.
A.
B.
C.
D.
44.
4.032
3.365
3.747
1.476
The table t value associated with the upper 10% of the t distribution and 17
degrees of freedom is _______.
A.
B.
C.
D.
E
Calc
A
The table t value associated with the upper 1% of the t distribution and 5 degrees
of freedom is _______.
4.604
2.776
2.132
2.353
The table t value associated with 10 degrees of freedom and used to compute a
95% confidence interval is _______.
A.
B.
C.
D.
1.812
2.228
3.169
1.372
246
Test Bank
B
46.
E
Calc
B
A.
B.
C.
D.
47.
E
Calc
C
48.
E
Calc
1.323
1.721
2.080
2.518
The table t value associated with 8 degrees of freedom and used to compute a 99%
confidence interval is _______.
A.
B.
C.
D.
49.
3.055
2.179
1.782
1.796
The table t value associated with 21 degrees of freedom and used to compute a
90% confidence interval is _______.
A.
B.
C.
D.
E
Calc
C
The table t value associated with 12 degrees of freedom and used to compute a
95% confidence interval is _______.
1.397
1.860
3.355
2.896
A researcher is interested in estimating the mean value for a population. She takes
a random sample of 17 items and computes a sample mean of 224 and a sample
standard deviation of 32. She decides to construct a 98% confidence interval to
estimate the mean. The degrees of freedom associated with this problem are
_______.
A.
B.
C.
D.
18
17
16
15
Chapter 8: Statistical Inference: Estimation for Single Populations 247
C
50.
The lengths of steel rods produced by a shearing process are normally distributed.
A random sample of 10 rods is selected; the sample mean length is 119.05 inches;
and the sample standard deviation is 0.10 inch. The 95% confidence interval for
the population mean rod length is ______________.
M
BCalc
A.
B.
C.
D.
A
The lengths of steel rods produced by a shearing process are normally distributed.
A random sample of 10 rods is selected; the sample mean length is 119.05 inches;
and the sample standard deviation is 0.10 inch. The 90% confidence interval for
the population mean rod length is ______________.
51.
118.99 to 119.11
118.82 to 119.28
118.98 to 119.12
118.85 to 119.25
M
BCalc
A.
B.
C.
D.
B
The weights of aluminum castings produced by a process are normally distributed.
A random sample of 5 castings is selected; the sample mean weight is 2.21
pounds; and the sample standard deviation is 0.12 pound. The 98% confidence
interval for the population mean casting weight is _________.
52.
118.99 to 119.11
118.87 to 119.23
119.00 to 119.10
118.89 to 119.21
M
BCalc
A.
B.
C.
D.
D
Life tests performed on a sample of 13 batteries of a new model indicated: (1) an
average life of 75 months, and (2) a standard deviation of 5 months. Other battery
models, produced by similar processes, have normally distributed life spans. The
98% confidence interval for the population mean life of the new model is
_________.
53.
M
BCalc
A.
B.
C.
D.
1.76 to 2.66
2.01 to 2.41
2.08 to 2.34
1.93 to 2.49
63.37 to 86.63
61.60 to 88.41
71.77 to 78.23
71.28 to 78.72
248
Test Bank
C
54.
Life tests performed on a sample of 13 batteries of a new model indicated: (1) an
average life of 75 months, and (2) a standard deviation of 5 months. Other battery
models, produced by similar processes, have normally distributed life spans. The
90% confidence interval for the population mean life of the new model is
_________.
M
BCalc
A.
B.
C.
D.
B
A researcher wants to estimate the proportion of the population which possess a
given characteristic. A random sample of size 800 is taken resulting in 360 items
which possess the characteristic. The point estimate for this population proportion
is _______.
55.
E
Calc
A
A.
B.
C.
D.
56.
M
Calc
B
M
Calc
0.55
0.45
0.35
0.65
A researcher wants to estimate the proportion of a population which possess a
given characteristic. A random sample of size 250 is taken and 40% of the sample
possess the characteristic. The 90% confidence interval to estimate the population
proportion is _______.
A.
B.
C.
D.
57.
66.78 to 83.23
72.72 to 77.28
72.53 to 77.47
66.09 to 83.91
0.35 to 0.45
0.34 to 0.46
0.37 to 0.43
0.39 to 0.41
A researcher wants to estimate the proportion of a population which possess a
given characteristic. A random sample of size 250 is taken and 40% of the sample
possess the characteristic. The 95% confidence interval to estimate the population
proportion is _______.
A.
B.
C.
D.
0.35 to 0.45
0.34 to 0.46
0.37 to 0.43
0.39 to 0.41
Chapter 8: Statistical Inference: Estimation for Single Populations 249
C
58.
M
Calc
B
A.
B.
C.
D.
59.
M
Calc
D
60.
M
Calc
0.53 to 0.67
0.25 to 0.35
0.24 to 0.36
0.27 to 0.33
A random sample of 225 items from a population results in 60% possessing a
given characteristic. Using this information, the researcher constructs a 99%
confidence interval to estimate the population proportion. The resulting
confidence interval is _______.
A.
B.
C.
D.
61.
0.53 to 0.67
0.25 to 0.35
0.24 to 0.36
0.27 to 0.33
A researcher wants to estimate the proportion of a population which possess a
given characteristic. A random sample of size 200 is taken and 30% of the sample
possess the characteristic. The 90% confidence interval to estimate the population
proportion is _______.
A.
B.
C.
D.
M
Calc
A
A researcher wants to estimate the proportion of a population which possess a
given characteristic. A random sample of size 200 is taken and 30% of the sample
possess the characteristic. The 95% confidence interval to estimate the population
proportion is _______.
0.54 to 0.66
0.59 to 0.61
0.57 to 0.63
0.52 to 0.68
A random sample of 225 items from a population results in 60% possessing a
given characteristic. Using this information, the researcher constructs a 90%
confidence interval to estimate the population proportion. The resulting
confidence interval is _______.
A.
B.
C.
D.
0.546 to 0.654
0.536 to 0.664
0.596 to 0.604
0.571 to 0.629
250
Test Bank
A
62.
Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for
non-business communications. A random sample of 200 e-mail messages was
selected. Thirty of the messages were not business related. The point estimate for
this population proportion is _______.

0.300
0.182
0.667
E
BApp
A.
B.
C.
D.
A
Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for
non-business communications. A random sample of 200 e-mail messages was
selected. Thirty of the messages were not business related. The 90% confidence
interval for the population proportion is _________.
63.
M
BCalc
A.
B.
C.
D.
D
Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for
non-business communications. A random sample of 200 e-mail messages was
selected. Thirty of the messages were not business related. The 95% confidence
interval for the population proportion is _________.
64.
0.108 to 0.192
0.153 to 0.247
0.091 to 0.209
0.145 to 0.255
M
BCalc
A.
B.
C.
D.
C
Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for
non-business communications. A random sample of 200 e-mail messages was
selected. Thirty of the messages were not business related. The 98% confidence
interval for the population proportion is _________.
65.
M
BCalc
A.
B.
C.
D.
0.108 to 0.192
0.153 to 0.247
0.091 to 0.209
0.101 to 0.199
0.108 to 0.192
0.153 to 0.247
0.091 to 0.209
0.145 to 0.255
Chapter 8: Statistical Inference: Estimation for Single Populations 251
A
66.
Catherine Chao, Director of Marketing Research, is evaluating consumer
acceptance of a new toothpaste package. She randomly selects a sample of 200
households. Forty households prefer the new package to all other package
designs. The point estimate for this population proportion is _______.
M
BCalc
A.
B.
C.
D.
B
Catherine Chao, Director of Marketing Research, is evaluating consumer
acceptance of a new toothpaste package. She randomly selects a sample of 200
households. Forty households prefer the new package to all other package
designs. The 90% confidence interval for the population proportion is
_________.
67.
0.20
0.25
0.40
0.45
M
BCalc
A.
B.
C.
D.
C
Catherine Chao, Director of Marketing Research, is evaluating consumer
acceptance of a new toothpaste package. She randomly selects a sample of 200
households. Forty households prefer the new package to all other package
designs. The 95% confidence interval for the population proportion is
_________.
68.
0.199 to 0.201
0.153 to 0.247
0.164 to 0.236
0.145 to 0.255
M
BCalc
A.
B.
C.
D.
C
Ophelia O'Brien, VP of Consumer Credit of American First Banks (AFB), has
implemented a 'fast feedback' to keep her informed of the default rate on personal
loans at the AFB member banks. On each Friday, the default rate is calculated for
a sample of 500 personal loans. Last Friday's sample contained 30 defaulted
loans. The point estimate for this population proportion is _______.
69.
M
BCalc
A.
B.
C.
D.
0.153 to 0.247
0.199 to 02.01
0.145 to 0.255
0.198 to 0.202
0.0002
16.670
0.0600
0.0333
252
Test Bank
A
70.
Ophelia O'Brien, VP of Consumer Credit of American First Banks (AFB), has
implemented a 'fast feedback' to keep her informed of the default rate on personal
loans at the AFB member banks. On each Friday, the default rate is calculated for
a sample of 500 personal loans. Last Friday's sample contained 30 defaulted
loans. The 90% confidence interval for the population proportion is _________.
M
BCalc
A.
B.
C.
D.
D
Ophelia O'Brien, VP of Consumer Credit of American First Banks (AFB), has
implemented a 'fast feedback' to keep her informed of the default rate on personal
loans at the AFB member banks. On each Friday, the default rate is calculated for
a sample of 500 personal loans. Last Friday's sample contained 30 defaulted
loans. The 95% confidence interval for the population proportion is _________.
71.
0.043 to 0.077
0.046 to 0.074
0.039 to 0.081
0.028 to 0.060
M
BCalc
A.
B.
C.
D.
A
Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service
level provided to walk-in customers. Brian would like to minimize the variance
of waiting time for these customers, since this would mean each customer
received the same level of service. Accordingly, his staff recorded the waiting
times for 15 randomly selected walk-in customers, and determined that their mean
waiting time was 15 minutes and that the variance was 4 minutes. The 90%
confidence interval for the population variance of waiting times is ________.
72.
M
BCalc
A.
B.
C.
D.
0.043 to 0.077
0.046 to 0.074
0.028 to 0.060
0.039 to 0.081
9.46 to 34.09
56.25 to 64.87
11.05 to 16.03
8.58 to 39.79
Chapter 8: Statistical Inference: Estimation for Single Populations 253
D
73.
Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service
level provided to walk-in customers. Brian would like to minimize the variance
of waiting time for these customers, since this would mean each customer
received the same level of service. Accordingly, his staff recorded the waiting
times for 15 randomly selected walk-in customers, and determined that their mean
waiting time was 15 minutes and that the variance was 4 minutes. The 95%
confidence interval for the population variance of waiting times is ________.
M
BCalc
A.
B.
C.
D.
C
Velma Vasquez, fund manager of the Vasquez Value Fund, manages a portfolio
of 250 common stocks. Velma relies on various statistics, such as variance, to
assess the overall risk of stocks in an economic sector. Her staff reported that for a
sample 14 utility stocks the mean annualized return was 14% and that the variance
was 3%. The 90% confidence interval for the population variance of annualized
returns is _______.
74.
9.46 to 34.09
56.25 to 64.87
11.05 to 16.03
8.58 to 39.79
M
BCalc
A.
B.
C.
D.
B
Velma Vasquez, fund manager of the Vasquez Value Fund, manages a portfolio
of 250 common stocks. Velma relies on various statistics, such as variance, to
assess the overall risk of stocks in an economic sector. Her staff reported that for a
sample 14 utility stocks the mean annualized return was 14% and that the variance
was 3%. The 95% confidence interval for the population variance of annualized
returns is _______.
75.
M
BCalc
A.
B.
C.
D.
0.018 to 0.064
0.016 to 0.078
0.017 to 0.066
0.016 to 0.075
0.018 to 0.064
0.016 to 0.078
0.017 to 0.066
0.016 to 0.075
254
Test Bank
D
76.
James Desreumaux, VP of Human Resources of American First Banks (AFB), is
reviewing the employee training programs of AFB banks. His staff randomly
selected personnel files for 10 tellers in the Southwest Region, and determined
that their mean training time was 25 hours and that the standard deviation was 5
hours. The 90% confidence interval for the population variance of training times
is ________.
M
BCalc
A.
B.
C.
D.
A
James Desreumaux, VP of Human Resources of American First Banks (AFB), is
reviewing the employee training programs of AFB banks. His staff randomly
selected personnel files for 10 tellers in the Southwest Region, and determined
that their mean training time was 25 hours and that the standard deviation was 5
hours. The 95% confidence interval for the population variance of training times
is ________.
77.
11.83 to 83.33
2.37 to 16.67
2.66 to 13.51
13.30 to 67.57
M
BCalc
A.
B.
C.
D.
B
The finite correction factor should be used if the sample size is _______.
78.
11.83 to 83.33
2.37 to 16.67
2.66 to 13.51
13.30 to 67.57
M
Term
A.
B.
C.
D.
B
In finding a confidence interval for the population mean, the population standard
deviation should be used if it is known. If the population standard deviation is not
known, then it should be estimated with _______.
79.
E
Term
A.
B.
C.
D.
less than 5% of the population size
more than 5% of the population size
less than 30
more than 100
the sample variance
the sample standard deviation
the range
the mean
Chapter 8: Statistical Inference: Estimation for Single Populations 255
A
80.
M
Calc
A
What proportion of a population possesses a given characteristic? To estimate
this, a random sample of 1700 people are interviewed from the population. Seven
hundred and fourteen of the people sampled possess the characteristic. Using this
information, the researcher computes an 88% confidence interval to estimate the
proportion of the population who possess the given characteristic. The resulting
confidence interval is _______.
A.
B.
C.
D.
81.
0.401 to 0.439
0.409 to 0.431
0.392 to 0.448
0.389 to 0.451
In estimating the sample size necessary to estimate a population mean, the error of
estimation, E, is equal to _______.
E
Term
A.
B.
C.
D.
B
In estimating sample size, if the population standard deviation is unknown, it can
be estimated by using _______.
82.
the distance between the sample mean and the population mean
the distance between the sample mean and the variance
the Z score
the sample size
M
Term
A.
B.
C.
D.
C
Suppose a researcher wants to conduct a study to estimate the population mean.
He plans to use a 95% level of confidence to estimate the mean, and the
population standard deviation is approximately 34. The researcher wants the error
to be no more than 4. The sample size should be at least _______.
M
Calc
83.
A.
B.
C.
D.
the population mean
one-fourth of the range
one-half of the range
the Z score
7
196
278
1110
256
Test Bank
B
84.
James Desreumaux, VP of Human Resources of American First Banks (AFB), is
reviewing the employee training programs of AFB banks. He plans to use a 95%
confidence interval estimate of mean training time of tellers and is willing to
accept an error of 1 hour; previous studies indicated a standard deviation of 2
hours. The sample size should be at least _______.
M
BCalc
A.
B.
C.
D.
B
James Desreumaux, VP of Human Resources of American First Banks (AFB), is
reviewing the employee training programs of AFB banks. He plans to use a 90%
confidence interval estimate of mean training time of tellers and is willing to
accept an error of 1 hour; previous studies indicated a standard deviation of 5
hours. The sample size should be at least _______.
85.
4
16
34
68
M
BCalc
A.
B.
C.
D.
A
A researcher wants to determine the sample size necessary to adequately conduct
a study to estimate the population mean to within 5 points. The range of
population values is 80 and the researcher plans to use a 90% level of confidence.
The sample size should be at least _______.
86.
M
Calc
C
M
Calc
A.
B.
C.
D.
87.
4
16
34
68
44
62
216
692
A study is going to be conducted in which a population mean will be estimated
using a 92% confidence interval. The estimate needs to be within 12 of the actual
population mean. The population variance is estimated to be around 2500. The
necessary sample size should be at least _______.
A.
B.
C.
D.
15
47
53
638
Chapter 8: Statistical Inference: Estimation for Single Populations 257
B
88.
In estimating the sample size necessary to estimate P, if there is no good
approximation for the value of P available, the value of ____ should be used as an
estimate of P in the formula.
E
Term
A.
B.
C.
D.
D
A researcher wants to estimate the population proportion with a 95% level of
confidence. He estimates from previous studies that the population proportion is
no more than .30. The researcher wants the estimate to have an error of no more
than .03. The necessary sample size is at least _______.
89.
M
Calc
C
A.
B.
C.
D.
90.
0.10
0.50
0.40
1.96
27
188
211
897
Catherine Chao, Director of Marketing Research, is evaluating consumer
acceptance of a new toothpaste package. She plans to use a 95% confidence
interval estimate of the proportion of households which prefer the new packages;
she will accept a 0.05 error. Previous studies indicate that new packaging has an
approximately 70% acceptance rate. The sample size should be at least _______.
M
BCalc
A.
B.
C.
D.
B
Catherine Chao, Director of Marketing Research, is evaluating consumer
acceptance of a new toothpaste package. She plans to use a 80% confidence
interval estimate of the proportion of households which prefer the new packages;
she will accept a 0.05 error. Previous studies indicate that new packaging has an
approximately 70% acceptance rate. The sample size should be at least _______.
91.
M
BCalc
A.
B.
C.
D.
27
59
323
427
27
59
323
427
258
Test Bank
A
92.
Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for
non-business communications. He plans to use a 95% confidence interval estimate
of the proportion of e-mail messages that are non-business; he will accept a 0.05
error. Previous studies indicate that approximately 30% of employee e-mail is not
business related. Elwin should sample _______ e-mail messages.

12
457
14
E
BApp
A.
B.
C.
D.
C
Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for
non-business communications. He plans to use a 98% confidence interval estimate
of the proportion of e-mail messages that are non-business; he will accept a 0.05
error. Previous studies indicate that approximately 30% of employee e-mail is not
business related. Elwin should sample _______ e-mail messages.
93.

12
457
14
E
BApp
A.
B.
C.
D.
D
A researcher wants to estimate the population proportion with a 90% level of
confidence. She estimates from previous studies that the population proportion is
no more than .30. The researcher wants the estimate to have an error of no more
than .02. The necessary sample size is at least _______.
94.
M
Calc
A
M
Calc
A.
B.
C.
D.
95.
29
47
298
1421
A study will be conducted to estimate the population proportion. A level of
confidence of 99% will be used and an error of no more than .04 is desired. There
is no knowledge as to what the population proportion will be. The size of sample
should be at least _______.
A.
B.
C.
D.
1036
160
41
259
Chapter 8: Statistical Inference: Estimation for Single Populations 259
D
96.
M
Calc
B
A.
B.
C.
D.
97.
M
Calc
C
98.
M
BCalc
73
384
95
277
You wish to determine the proportion of all secretaries who are familiar with a
particular word processing package. You will conduct a random survey. How
large a sample should you take if you want to be 90% confident of the results and
within 0.04 of the true population proportion?
A.
B.
C.
D.
99.
41
313
1677
1373
You wish to determine the proportion of all secretaries who are familiar with a
particular word processing package. You will conduct a random survey. How
large a sample should you take if you want to be 95% confident of the results and
within 0.05 of the true population proportion?
A.
B.
C.
D.
M
Calc
B
A researcher conducts a study to determine what the population proportion is for a
given characteristic. It is believed from previous studies that the proportion of the
population will be at least .65. The researcher wants to use a 98% level of
confidence. He also wants the error to be no more than .03. The sample size
should be at least _______.
152
216
423
600
A bank officer wishes to estimate the amount of the average total deposits per
customer at the bank. She wishes the estimate to be within $200 of the actual
average with 95% confidence. She assumes the standard deviation for this should
be $1000. How large should the sample be?
A.
B.
C.
D.
10
96
68
19,208
260
Test Bank
B 100.
A bank officer wishes to estimate the amount of the average total deposits per
customer at the bank. She wishes the estimate to be within $100 of the actual
average with 90% confidence. She assumes the standard deviation for this should
be $800. How large should the sample be?
M
BCalc
A.
B.
C.
D.
51
173
246
17,318
Chapter 8: Statistical Inference: Estimation for Single Populations 261
101.
M
BApp
While evaluating the service level provided to walk-in customers, Brian Vanecek,
VP of Operations at Portland Trust Bank, encountered resistance to some of his
proposals from fellow executives. Brian focuses on providing timely, efficient
service to the banks customers; customers having to wait for service upsets him;
and some customers share his philosophy, but not all. The VP of Marketing
points out that some customers (for various reasons) "don't want to rush in and
out." Moreover, the bank's management wants to provide a warm friendly
atmosphere for customers.
Identify some potential segments of the bank's walk-in customers. (Are drivethrough customers a distinct segment?) How can a statistical analysis of walk-in
customers help identify and evaluate service alternatives for the segments? What
estimates are needed?
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
262
Test Bank
102.
Stockton Steel, Inc. can qualify for a lucrative contract to supply steel rods if it
can meet the buyer’s process capability requirements. Specifically, the buyer
requires documented evidence that the standard deviation of Stockton's process is
no more than 1/12th of the difference between the upper tolerance limit and the
lower tolerance limit,   (UTL - LTL)/12.
Sarah Shum, Director of Quality Programs, is assigned the task of developing the
documentation. She knows that variability of the rod length depends on several
factors: the operators' skill, the mix used in the steel melt, the quality of materials
used in the mix, and the condition of the equipment.
M
BApp
Discuss Sarah's assignment. What estimates does she need? Which departments
must participate in the process capability study? Which of these departments will
not participate after completion of the study?
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Chapter 8: Statistical Inference: Estimation for Single Populations 263
103.
Alan Lessoff, VP of Marketing at CyberWarehouse, Inc. (CWI), wants to learn
more about online shoppers that visit the CyperWarehouse web sites.
Identify some potential segments of the CWI's online shoppers. (Are repeatvisitors a distinct segment?) How can a statistical analysis of online shoppers
help identify and evaluate service alternatives, merchandise selection, and web
site design for the segments? What estimates are needed?
M
BApp
264
Test Bank
104.
Online financial brokerages continue go grow with the Internet. CyberMarkets,
Inc. (CMI) advises e-commerce businesses on their marketing strategies.
Addalie McMinn, VP of Research at CMI, expects increasingly intense
competition between online brokerages for new customers as the industry
matures.
She wants to learn more about the customers of online brokerages; she wants to
understand "what makes them tick" so she can advise CMI clients how to compete
more successfully. What factors do these investors use to choose one broker over
another? Transaction costs? Basic service characteristics such as fast order
execution, and timely, well-organized statements? Free tie-in services such as an
address book, a calendar service, and links to favorite web sites for gifts.
Should Addalie segment the customer population? Are all factors equally
important for all market segments? Does age, gender, or professional occupation
matter?
How can a statistical analysis of online brokerage customers assist with stategy
formulation? Describe the statistical methods that will be useful to Addalie
during the study. What estimates are needed?
M
BApp