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might have become careless in counting due to an increase in the volume of prescriptions. To
test her theory she randomly selects 40 prescriptions requiring 60 tablets and recounts the
number in each bottle. She finds a sample mean of 62.05 and a standard deviation of 4.45.
Calculate a confidence interval to test the hypotheses at α = .002.
A. [59.73 64.37]
B. [59.88 64.22]
C. [60.24 63.86]
D. [60.67 63.43]
E. [61.15 62.95] 1740 Chapter 01  An Introduction to Business Statistics 115. Last year, during an investigation of the time spent reading emails on a daily basis,
researchers found that on Monday the average time was 50 minutes. Office workers claim that
with the increased spam and junk mail, this time has now increased. To conduct a test, a
sample of 25 employees is selected with the following results: sample mean = 51.05 minutes
and sample standard deviation = 4.42 minutes. Calculate the appropriate test statistic to test
the hypothesis that the time has increased from last year.
A. 2.38
B. 1.19
C. 1.19
D. 1.76
E. 1.76 116. Last year, during an investigation of the time spent reading emails on a daily basis,
researchers found that on Monday the average time was 50 minutes. Office workers claim that
with the increased spam and junk mail, this time has now increased. To conduct a test, a
sample of 25 employees is selected with the following results: sample mean = 51.05 minutes
and sample standard deviation = 14.2 minutes. What is the critical value for α = .05 to test the
hypotheses.
A. 1.711
B. 2.064
C. 2.060
D. 1.708
E. 1.645 117. The manager of a local specialty store is concerned with a possible slowdown in
payments by her customers. She measures the rate of payment in terms of the average number
of days receivables are outstanding. Generally, the store has maintained an average of 50 days
with a standard deviation of 10 days. A random sample of 25 accounts gives an average of 54
days outstanding with a standard deviation of 8 days. Calculate the appropriate test statistic to
test the hypotheses.
A. 2.00
B. 2.50
C. 12.50
D. 2.50
E. 2.00 1741 Chapter 01  An Introduction to Business Statistics 118. The manager of a local specialty store is concerned with a possible slowdown in
payments by her customers. She measures the rate of payment in terms of the average number
of days receivables are outstanding. Generally, the store has maintained an average of 50 days
with a standard deviation of 10 days. A random sample of 25 accounts gives an average of 54
days outstanding with a standard deviation of 8 days. What is the critical value for α = .01 to
test the hypotheses.
A. 2.485
B. 2.797
C. 2.492
D. 2.787
E. 2.327 119. In research on cell phone use by teenagers it was found that the average connect time for
a call was at least 15 minutes. Social psychologists feel that this study understated the time.
To determine this claim, cell phone bills for 15 teenagers were evaluated. On average, the
time spent was 18.5 minutes with a sample standard deviation of four minutes (assume a
normal distribution). Calculate the appropriate test statistic to test the hypotheses.
A. 3.39
B. 13.125
C. 0.875
D. 0.875
E. 3.39 120. In research on cell phone use by teenagers it was found that the average connect time for
a call was at least 15 minutes. Social psychologists feel that this study understated the time.
To determine this claim, cell phone bills for 15 teenagers were evaluated. On average, the
time spent was 18.5 minutes with a sample standard deviation of four minutes (assume a
normal distribution). What is the critical value for α = .001 to test the hypotheses.
A. 4.140
B. 4.140
C. 4.073
D. 3.291
E. 3.787 1742 Chapter 01  An Introduction to Business Statistics 121. The quality control manager of a major cell phone provider is concerned about the life of
the cell phone batteries they use. He took a sample of 13 batteries from a recent shipment and
used them continuously until they failed to work. The manager measured the number of hours
the batteries lasted and found the mean to be 550.4 with a standard deviation of 315.3.
Calculate the appropriate test statistic to test the claim that the mean life of the batteries is
more than 400 hours.
A. 6.20
B. 1.72
C. 0.477
D. 6.20
E. 1.72 122. The quality control manager of a major cell phone provider is concerned about the life of
the cell phone batteries they use. He took a sample of 13 batteries from a recent shipment and
used them continuously until they failed to work. The manager measured the number of hours
the batteries lasted and found the mean to be 550.4 with a standard deviation of 315.3. What
is the critical value for α = .10 to test the claim that the mean life of the batteries is more than
400 hours.
A. 1.356
B. 1.356
C. 1.282
D. 1.782
E. 1.782 123. In a bottling process, a manufacturer will lose money if the bottles contain either more or
less than is claimed on the label. Suppose a quality manager for a steak sauce company is
interested in testing whether the mean number of ounces of steak sa...
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 Winter '14

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