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Unformatted text preview: airline company is concerned that its proportion of late arrivals has substantially
increased in the past month. Historical data shows that on the average 18% of the company
airplanes have arrived late. In a random sample of 1,240 airplanes, 310 airplanes have arrived
late. If we are conducting a hypothesis test of a single proportion to determine if the
proportion of late arrivals has increased: What is the value of the calculated test statistic?
A. Z = 6.416
B. Z = 3.208
C. Z = 3.208
D. Z = 6.416
E. Z = 1.833 84. A mailorder business prides itself in its ability to fill customers' orders in less than six
calendar days, on average. Periodically, the operations manager selects a random sample of
customer orders and determines the number of days required to fill the orders. On one
occasion when a sample of 39 orders was selected, the average number of days was 6.65 with
a sample standard deviation of 1.5 days. Calculate the appropriate test statistic to test the
hypotheses.
A. 2.71
B. 16.90
C. 0.65
D. 2.71
E. 3.31 1730 Chapter 01  An Introduction to Business Statistics 85. A mailorder business prides itself in its ability to fill customers' orders in less than six
calendar days, on average. Periodically, the operations manager selects a random sample of
customer orders and determines the number of days required to fill the orders. On one
occasion when a sample of 39 orders was selected, the average number of days was 6.65 with
a sample standard deviation of 1.5 days. What is the critical value for α = .10 to test the
hypotheses.
A. 1.28
B. 1.96
C. 2.33
D. 1.28
E. 1.96 86. A random sample of 80 companies who announced corrections to their balance sheets
took a mean time of 8.1 days for the time between balance sheet construction and the
complete audit. The standard deviation of these times was 1.3 days. If the claim is that the
population mean is greater than 7.5 days, calculate the appropriate test statistic to test the
hypotheses.
A. 4.13
B. 36.92
C. 4.71
D. 4.71
E. 4.13 87. A random sample of 80 companies who announced corrections to their balance sheets
took a mean time of 8.1 days for the time between balance sheet construction and the
complete audit. The standard deviation of these times was 1.3 days. What is the critical value
for α = .001 to test the claim that µ is greater than 7.5 days.
A. 2.575
B. 3.09
C. 1.96
D. 2.575
E. 3.09 1731 Chapter 01  An Introduction to Business Statistics 88. The manufacturer of an overthecounter heartburn relief mediation claims that its product
brings relief in less than 3.5 minutes, on average. To be able to make this claim the
manufacturer was required by the FDA to present statistical evidence in support of the claim.
The manufacturer reported that for a sample of 50 heartburn sufferers, the mean time to relief
was 3.3 minutes and the standard deviation was 1.1 minutes. Calculate the appropriate test
statistic to test the hypotheses.
A. 1.29
B. 9.09
C. 1.29
D. 2.58
E. 9.09 89. The manufacturer of an overthecounter heartburn relief mediation claims that its product
brings relief in less than 3.5 minutes, on average. To be able to make this claim the
manufacturer was required by the FDA to present statistical evidence in support of the claim.
The manufacturer reported that for a sample of 50 heartburn sufferers, the mean time to relief
was 3.3 minutes and the standard deviation was 1.1 minutes. Calculate the pvalue that
corresponds to the test statistic.
A. 0.0985
B. 0.0001
C. 0.4015
D. 0.005
E. 0.985 90. A company has developed a new inkjet cartridge for its printer that it believes has a
longer lifetime on average than the one currently being produced. To investigate its length of
life, 225 of the new cartridges were tested by counting the number of highquality printed
pages each was able to produce. The sample mean and standard deviation were determined to
be 1511.4 pages and 35.7 pages, respectively. The historical average lifetime for cartridges
produced by the current process is 1502.5 pages. Calculate the appropriate test statistic to test
the hypotheses.
A. 56.09
B. 3.74
C. 22.34
D. 3.74
E. 22.34 1732 Chapter 01  An Introduction to Business Statistics 91. A company has developed a new inkjet cartridge for its printer that it believes has a
longer lifetime on average than the one currently being produced. To investigate its length of
life, 225 of the new cartridges were tested by counting the number of highquality printed
pages each was able to produce. The sample mean and standard deviation were determined to
be 1511.4 pages and 35.7 pages, respectively. The historical average lifetime for cartridges
produced by the current process is 1502.5 pages. What is the critical value for α = .05 to test
the hypotheses.
A. 1.645
B. 1.645
C. 1.96
D. 1.28
E. 1.96 92. When 100 randomly selected car owners are surveyed, it is found that the mean length of
time they plan to keep their car is 7.01 years, and the standard deviation is 3.74...
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This document was uploaded on 01/20/2014.
 Winter '14

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