Unformatted text preview: es are both more accurate and more precise than point estimates.
D. Interval estimates take into account the fact that the statistic being used to estimate the
population parameter is a random variable. 24. When the sample size and sample standard deviation remain the same, a 99% confidence
interval for a population mean, µ will be _________________ the 95% confidence interval
for µ.
A. Wider than
B. Narrower than
C. Equal to 25. 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
______________ a confidence interval for a population mean based on a sample of n = 50.
A. Wider than
B. Narrower than
C. Equal to 1616 Chapter 01  An Introduction to Business Statistics 26. When the level of confidence and the sample size remain the same, a confidence interval
for a population mean µ will be ________________, when the sample standard deviation s is
small than when s is large.
A. Wider
B. Narrower
C. Neither A nor B, they will be the same 27. When the sample size and the sample proportion
remain the same, a 90% confidence
interval for a population proportion p will be ______________ the 99% confidence interval
for p.
A. Wider than
B. Narrower than
C. Equal to 28. 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 ______________
a confidence interval for p based on a sample of n = 400.
A. Wider than
B. Narrower than
C. Equal to 29. When the level of confidence and sample size remain the same, a confidence interval for a
population proportion p will be ______________ when
is smaller.
A. Wider
B. Narrower
C. Neither A nor B, they will be the same 1617 is larger than when Chapter 01  An Introduction to Business Statistics 30. When the population is normally distributed, population standard deviation σ is unknown,
and the sample size is n = 15; the confidence interval for the population mean µ is based on:
A. The z (normal) distribution
B. The t distribution
C. The Binomial distribution
D. The Poisson distribution
E. None of the above 31. 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
A. Makes
B. Makes that: as small as reasonably possible
as large as reasonably possible C. Makes
as close to .5 as reasonably possible
D. Makes
as close to .25 as reasonably possible
E. Both B and D are correct 32. When a confidence interval for a population proportion is constructed for a sample size n
= 30 and the value of
= .4, the interval is based on:
A. The z distribution
B. The t distribution
C. The exponential distribution
D. The Poisson distribution
E. None of the above 33. There is little difference between the values of tα/2 and zα/2 when:
A. The sample size is small
B. The sample size is large
C. The sample mean is small
D. The sample mean is large
E. The sample standard deviation is small 1618 Chapter 01  An Introduction to Business Statistics 34. Assuming the same level of significance α, as the sample size increases, the value of ta/2
_____ approaches the value of
A. Always
B. Sometimes
C. Never . 35. In a manufacturing process a random sample of 9 bolts manufactured has a mean length of
3 inches with a variance of .09. What is the 90% confidence interval for the true mean length
of the bolt?
A. 2.8355 to 3.1645
B. 2.5065 to 3.4935
C. 2.4420 to 3.5580
D. 2.8140 to 3.8160
E. 2.9442 to 3.0558 36. In a manufacturing process a random sample of 9 bolts manufactured has a mean length of
3 inches with a standard deviation of .3 inches. What is the 95% confidence interval for the
true mean length of the bolt?
A. 2.804 to 3.196
B. 2.308 to 3.692
C. 2.770 to 3.231
D. 2.412 to 3.588
E. 2.814 to 3.186 37. In a manufacturing process a random sample of 36 bolts manufactured has a mean length
of 3 inches with a standard deviation of .3 inches. What is the 99% confidence interval for the
true mean length of the bolt?
A. 2.902 to 3.098
B. 2.884 to 3.117
C. 2.865 to 3.136
D. 2.228 to 3.772
E. 2.685 to 3.698 1619 Chapter 01  An Introduction to Business Statistics 38. The internal auditing staff of a local manufacturing company performs a sample audit
each quarter to estimate the proportion of accounts that are delinquent (more than 90 days
overdue). For this quarter, the auditing staff randomly selected 400 customer accounts and
found that 80 of these accounts were delinquent. What is the 95% confidence interval for the
proportion of all delinquent customer accounts at this manufacturing company?
A. .1608 to .2392
B. .1992 to .2008
C. .1671 to .2329
D. .1485 to .2515
E. .1714 to .2286 39. The internal auditing staff of a local manufacturing company performs a sample audit
each quarter to estimate the proportion of accounts that are current (between 0 and 60 days
after billing). The histor...
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