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food poisoning occurred with a sample of 319 patrons contacted. Of the 319 contacted, 29
indicated that they would not go back to the restaurant because of the potential for food
poisoning. What sample size would be needed in order to be 99% confident that the sample
proportion is within .02 of ρ, the true proportion of customers who refuse to go back to the
restaurant?
A. 14
B. 38
C. 129
D. 1,371
E. 1,777 72. In a survey of 308 adults, 17% listed jewelry among the romantic gifts men want to
receive. Construct the 98% confidence interval for the proportion of all adults who include
jewelry among their responses.
A. [.025 .085]
B. [.169 .171]
C. [.120 .220]
D. [.140 .200]
E. [.050 .170] 73. In a poll of 1,004 adults, 93% indicated that restaurants and bars should refuse service to
patrons who have had too much to drink. Construct the 90% confidence interval for the
proportion of all adults who feel the same way.
A. [.078 .108]
B. [.914 .946]
C. [.920 .940]
D. [.917 .943]
E. [.910 .950] 1631 Chapter 01  An Introduction to Business Statistics 74. At a sobriety checkpoint the sheriff's department screened 676 drivers and 6 were arrested
for DWI. Find the 92% confidence interval for the true proportion of drivers who were DWI
that evening.
A. [0.000 0.027]
B. [0.003 0.015]
C. [0.902 0.938]
D. [0.000 0.076]
E. [0.006 0.030] 75. The Ohio Department of Agriculture tested 203 fuel samples across the state in 1999 for
accuracy of the reported octane level. For premium grade, 14 out of 105 samples failed (they
didn't meet ASTM specification and the FTC Octane posting rule). Find a 99% confidence
interval for the true population proportion of premium grade fuelquality failures.
A. [.045 .221]
B. [.068 .198]
C. [.023 .115]
D. [.047 .219]
E. [.100 .276] 76. The Ohio Department of Agriculture tested 203 fuel samples across the state in 1999 for
accuracy of the reported octane level. For premium grade, 14 out of 105 samples failed (they
didn't meet ASTM specification and the FTC Octane posting rule). How many samples would
be needed to create a 99% confidence interval that is within 0.02 of the true proportion of
premium grade fuelquality failures?
A. 4148
B. 2838
C. 1913
D. 744
E. 54 1632 Chapter 01  An Introduction to Business Statistics 77. To investigate the rate at which employees with cancer are fired or laid off, a telephone
survey was taken of 100 cancer survivors who worked while undergoing treatment. Seven (7)
were either fired or laid off due to their illness. Construct a 90% confidence interval for the
true percentage of all cancer patients who are fired or laid off due to their illness.
A. [0.0000 0.2034]
B. [0.0371 0.1029]
C. [0.0039 0.1361]
D. [0.0278 0.1122]
E. [0.0078 0.1400] 78. In 1995, 13,000 WWW users were surveyed and asked about their willingness to pay fees
for access to websites. Of these, 2,938 were definitely not willing to pay such fees. Construct
a 95% confidence interval for the proportion definitely unwilling to pay fees.
A. [0.286 0.302]
B. [0.219 0.233]
C. [0.220 0.232]
D. [0.212 0.241]
E. [0.214 0.245] 79. In 1995, 13,000 WWW users were surveyed and asked about their willingness to pay fees
for access to websites. Of these, 2,938 were definitely not willing to pay such fees. How large
a sample is necessary to estimate the proportion of interest to within 2% in a 95% confidence
interval?
A. 18
B. 307
C. 1717
D. 2000
E. 2965 80. In the construction of a confidence interval, as the confidence level required in estimating
the mean increases, the width of the confidence interval ______________.
A. Stays the same
B. Decreases
C. Increases 1633 Chapter 01  An Introduction to Business Statistics 81. As the sample size n increases, the width of the confidence interval _______________.
A. Stays the same
B. Decreases
C. Increases 82. When establishing the confidence interval for the average weight of a cereal box, assume
that the population standard deviation is known to be 2 ounces, and based on a sample the
average weight of a sample of 20 boxes is 16 ounces. The appropriate test statistics to use is
________.
A. t
B. Z
C. χ
D. p 83. As the significance level, α increases, the width of the confidence interval
_______________.
A. Stays the same
B. Decreases
C. Increases 84. As the standard deviation, (σ) decreases, the width of the confidence interval
_______________.
A. Stays the same
B. Decreases
C. Increases 85. As the stated confidence level decreases, the width of the confidence interval
_______________.
A. Stays the same
B. Decreases
C. Increases 1634 Chapter 01  An Introduction to Business Statistics 86. As the margin of error decreases, the width of the confidence interval _______________.
A. Stays the same
B. Decreases
C. Increases 87. If everything else is held constant, decreasing the margin of error, __________ the
required sample size.
A. Stays the same
B. Decreases
C. Increases 88. A confidence interval for the population mean is an interval constructed around the
_____.
A. Sample mean
B. Population mean
C. Z test statistic
D. t test statistic 89. In determining the sample size to estimate...
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