Unformatted text preview: customer accounts is within .03 of the true proportion of all
current accounts for this company.
A. 1842
B. 1548
C. 897
D. 632
E. 1267 AACSB: Analytic
Bloom's: Application
Difficulty: Hard
Topic: Sample size determination for population proportion 1662 Chapter 01  An Introduction to Business Statistics 40. In a manufacturing process, we are interested in measuring the average length of a certain
type of bolt. Past data indicates that the standard deviation is .25 inches. How many bolts
should be sampled in order to make us 95% confident that the sample mean bolt length is
within .02 inches of the true mean bolt length?
A. 25
B. 49
C. 423
D. 601
E. 1225 AACSB: Analytic
Bloom's: Application
Difficulty: Hard
Topic: Sample size determination for population mean 41. In a manufacturing process, we are interested in measuring the average length of a certain
type of bolt. Based on a preliminary sample of 9 bolts, the sample standard deviation is .3
inches. How many bolts should be sampled in order to make us 95% confident that the sample
mean bolt length is within .02 inches of the true mean bolt length?
A. 865
B. 80
C. 1470
D. 3989
E. 1197 AACSB: Analytic
Bloom's: Application
Difficulty: Hard
Topic: Sample size determination for population mean 1663 Chapter 01  An Introduction to Business Statistics 42. A company is interested in estimating
, the mean number of days of sick leave taken
by its employees. The firm's statistician randomly selects 100 personnel files and notes the
number of sick days taken by each employee. The sample mean is 12.2 days and the sample
standard deviation is 10 days. Calculate a 93% confidence interval for
, the mean number
of days of sick leave.
A. [10.725 13.675]
B. [10.390 14.010]
C. [12.019 12.381]
D. [12.053 12.348]
E. [11.735 12.665] AACSB: Analytic
Bloom's: Application
Difficulty: Hard
Topic: Confidence interval for population mean σ unknown 43. A company is interested in estimating
, the mean number of days of sick leave taken
by its employees. The firm's statistician randomly selects 100 personnel files and notes the
number of sick days taken by each employee. The sample mean is 12.2 days and the sample
standard deviation is 10 days. How many personnel files would the director have to select in
order to estimate µ to within 2 days with a 99% confidence interval?
A. 2
B. 13
C. 136
D. 165
E. 166 AACSB: Analytic
Bloom's: Application
Difficulty: Hard
Topic: Sample size determination for population mean 1664 Chapter 01  An Introduction to Business Statistics 44. The state highway department is studying traffic patterns on one of the busiest highways
in the state. As part of the study, the department needs to estimate the average number of
vehicles that pass an intersection each day. A random sample of 64 days gives us a sample
mean of 14,205 cars and a sample standard deviation of 1,010 cars. What is the 92%
confidence interval estimate of µ, the mean number of cars passing the intersection?
A. [12,438 15,972]
B. [14,028 14,382]
C. [12,189 14,221]
D. [13,984 14,426]
E. [14,183 14,227] AACSB: Analytic
Bloom's: Application
Difficulty: Medium
Topic: Confidence interval for population mean σ unknown 45. The state highway department is studying traffic patterns on one of the busiest highways
in the state. As part of the study, the department needs to estimate the average number of
vehicles that pass an intersection each day. A random sample of 64 days gives us a sample
mean of 14,205 cars and a sample standard deviation of 1,010 cars. After calculating the
confidence interval, the highway department officials decide that the precision is too low for
their needs. They feel the precision should be 300 cars. Given this precision, and needing to
be 99% confident, how many days do they need to sample?
A. 109
B. 76
C. 75
D. 62
E. 9 AACSB: Analytic
Bloom's: Application
Difficulty: Hard
Topic: Sample size determination for population mean 1665 Chapter 01  An Introduction to Business Statistics 46. The U.S. Department of Health and Human Services collected sample data for 772 males
between the ages of 18 and 24. That sample group has a mean height of 69.7 inches with a
standard deviation of 2.8 inches. Find the 99% confidence interval for the mean height of all
males between the ages of 18 and 24.
A. [63.19 76.21]
B. [62.49 76.91]
C. [69.65 69.75]
D. [69.47 69.93]
E. [69.44 69.96] AACSB: Analytic
Bloom's: Application
Difficulty: Medium
Topic: Confidence interval for population mean σ unknown 47. In a study of factors affecting soldiers' decisions to reenlist, 320 subjects were measured
for an index of satisfaction and the sample mean is 28.8 and the sample standard deviation is
7.3. Use the given sample data to construct the 98% confidence interval for the population
mean.
A. [27.85 29.75]
B. [27.96 29.64]
C. [11.82 45.78]
D. [28.75 28.85]
E. [28.60 29.00] AACSB: Analytic
Bloom's: Application
Difficulty: Hard
Topic: Confidence interval for population mean σ unknown 1666 Chapter 01  An Introduction to Business Statistics 48. A psychologist is collecting data on the time it takes to learn a certain tas...
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 Winter '14
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