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Unformatted text preview: uring the past year.
A. [11.06 12.14]
B. [11.34 11.86]
C. [10.44 12.76]
D. [11.15 12.05]
E. [3.56 19.64] 144. Unoccupied seats on flights cause airlines to lose revenue. Suppose a large airline wants
to estimate its average number of unoccupied seats per flight over the past year. 225 flight
records are randomly selected and the number of unoccupied seats is noted with a sample
mean of 11.6 seats and a standard deviation of 4.1 seats. How many flights should we select if
we wish to estimate µ to within 5 seats and be 95% confident?
A. 44
B. 3
C. 2
D. 110
E. 6 1649 Chapter 01  An Introduction to Business Statistics Chapter 08 Confidence Intervals Answer Key True / False Questions 1. The t distribution always has n degrees of freedom.
FALSE AACSB: Reflective Thinking
Bloom's: Knowledge
Difficulty: Easy
Topic: Confidence interval for population mean σ unknown 2. When the margin of error is added to and subtracted from the sample mean an interval is
formed that will contain µ with probability of (1  α).
TRUE AACSB: Reflective Thinking
Bloom's: Knowledge
Difficulty: Medium
Topic: Confidence interval for population mean 3. The standard error of the sample mean is s/√n.
TRUE AACSB: Reflective Thinking
Bloom's: Knowledge
Difficulty: Medium
Topic: Confidence interval for population mean 1650 Chapter 01  An Introduction to Business Statistics 4. Assuming the same level of significance α, as the sample size increases, the value of
tα/2approaches the value of zα/2.
TRUE AACSB: Reflective Thinking
Bloom's: Knowledge
Difficulty: Medium
Topic: Confidence interval for population mean σ unknown 5. When constructing a confidence interval for a sample proportion, the t distribution is
appropriate if the sample size is small.
FALSE AACSB: Reflective Thinking
Bloom's: Knowledge
Difficulty: Medium
Topic: Confidence interval for population proportion 6. First a 90% confidence interval is constructed from a sample size of 100. Then, for the
same identical data, a 92% confidence interval is constructed. The width of the 90% interval
is wider than the 92% confidence interval.
FALSE AACSB: Reflective Thinking
Bloom's: Comprehension
Difficulty: Medium
Topic: Confidence interval 7. When the population is normally distributed and the population standard deviation σ is
unknown, then for any sample size n, the sampling distribution of
is based on the z
distribution.
FALSE AACSB: Reflective Thinking
Bloom's: Knowledge
Difficulty: Medium
Topic: Confidence interval for population mean σ unknown 1651 Chapter 01  An Introduction to Business Statistics 8. When the sample size and sample standard deviation remain the same, a 99% confidence
interval for a population mean, µ will be narrower than the 95% confidence interval for µ.
FALSE AACSB: Reflective Thinking
Bloom's: Comprehension
Difficulty: Medium
Topic: Confidence interval for population mean σ unknown 9. When the level of confidence and sample standard deviation remain the same, a confidence
interval for a population mean based on a sample of n = 100 will be narrower than a
confidence interval for a population mean based on a sample of n = 50.
TRUE AACSB: Reflective Thinking
Bloom's: Comprehension
Difficulty: Medium
Topic: Confidence interval for population mean σ unknown 10. When the level of confidence and the sample size remain the same, a confidence interval
for a population mean µ will be wider, when the sample standard deviation s is small than
when s is large.
FALSE AACSB: Reflective Thinking
Bloom's: Comprehension
Difficulty: Medium
Topic: Confidence interval for population mean σ unknown 11. When the level of confidence and sample proportion
remain the same, a confidence
interval for a population proportion p based on a sample of n = 100 will be wider than a
confidence interval for p based on a sample of n = 400.
FALSE AACSB: Reflective Thinking
Bloom's: Comprehension
Difficulty: Medium
Topic: Confidence interval for population proportion 1652 Chapter 01  An Introduction to Business Statistics 12. When the level of confidence and sample size remain the same, a confidence interval for a
population proportion p will be narrower when
is larger than when
is
smaller.
FALSE AACSB: Reflective Thinking
Bloom's: Comprehension
Difficulty: Medium
Topic: Confidence interval for population proportion 13. When solving for the sample size needed to compute a 95% confidence interval for a
population proportion "p", having a given error bound "B", we choose a value of
makes
as small as reasonably possible.
FALSE that AACSB: Reflective Thinking
Bloom's: Comprehension
Difficulty: Medium
Topic: Sample size determination for population proportion 14. When determining the sample size n, if the value found for n is 79.2, we would choose to
sample 79 observations.
FALSE AACSB: Reflective Thinking
Bloom's: Knowledge
Difficulty: Medium
Topic: Sample size determination 1653 Chapter 01  An Introduction to Business Statistics
Multiple Choice Questions 15. The t distribution approaches the _______________ as the sample size ___________.
A. Binomial, increases
B. Binomial, decreases
C. Z, decreases
D. Z, increase...
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 Winter '14

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