Unformatted text preview: llege is conducting independent tests to determine
the distance a particular make of automobile will travel while consuming only 1 gallon of gas.
A sample of five cars is tested and a mean of 28.2 miles is obtained. How many cars should
the environmental group test if they wish to estimate µ, mean miles per 1 gallon, to within 0.5
miles and be 99% confident? Assume a population standard deviation of 2.7 miles.
A. 25
B. 124
C. 194
D. 618
E. 619 1627 Chapter 01  An Introduction to Business Statistics 62. A sociologist develops a test designed to measure a person's attitudes about disabled
people, and 16 randomly selected subjects are given the test. Their mean score is 71.2 with a
standard deviation of 10.5. Construct the 99% confidence interval for the mean score of all
subjects.
A. [40.26 102.14]
B. [63.46 78.94]
C. [60.66 81.74]
D. [64.44 77.96]
E. [63.21 79.19] 63. There is an average of 22.455 employees at 22 office furniture dealers in a major
metropolitan area with a standard deviation of 18.52. Construct a 99% confidence interval for
the true mean number of fulltime employees at office furniture dealers.
A. [11.014 33.896]
B. [11.277 33.633]
C. [12.284 32.626]
D. [12.513 32.397]
E. [20.072 24.838] 64. A federal bank examiner is interested in estimating the mean outstanding defaulted loans
balance of all defaulted loans over the last three years. A random sample of 20 defaulted loans
yielded a mean of $67,918 with a standard deviation of $16,552.40. Calculate a 90%
confidence interval for the mean balance of defaulted loans over the past three years.
A. [66,487 69,349]
B. [39,299 96,537]
C. [57,329 78,507]
D. [61,829 74,007]
E. [61,519 74,317] 1628 Chapter 01  An Introduction to Business Statistics 65. An experiment was conducted to determine the effectiveness of a method designed to
remove oil wastes found in soil. Three contaminated soil samples were treated. After 95 days,
the percentage of contamination removed from each soil sample was measured with a mean of
49.3% and a standard deviation of 1.5%. Estimate the mean percentage of contamination
removed at a 98% confidence level.
A. [48.36 50.24]
B. [43.27 55.33]
C. [47.29 51.31]
D. [47.88 50.72]
E. [46.47 52.13] 66. An experiment was conducted to determine the effectiveness of a method designed to
remove oil wastes found in soil. Three contaminated soil samples were treated. After 95 days,
the percentage of contamination removed from each soil sample was measured with a mean of
49.3% and a standard deviation of 1.5%. If we wished to narrow the boundary around µ for a
98% confidence interval to within 0.5%, how many soil samples should be in our experiment.
A. 437
B. 33
C. 9
D. 6
E. 3 67. A botanist measures the heights of 16 seedlings and obtains a mean and standard deviation
of 72.5 cm and 4.5 cm, respectively. Find the 95% confidence interval for the mean height of
seedlings in the population form which the sample was selected.
A. [62.91 82.09]
B. [70.30 74.70]
C. [70.10 74.90]
D. [70.54 74.46]
E. [71.90 73.10] 1629 Chapter 01  An Introduction to Business Statistics 68. On a standard IQ test, the standard deviation is 15. How many random IQ scores must be
obtained if we want to find the true population mean (with an allowable error of 0.5) and we
want 97% confidence in the results?
A. 4,239
B. 283
C. 212
D. 131
E. 66 69. A manufacturer of dodge balls uses a machine to inflate its new balls to a pressure of 13.5
pounds (
= 0.1). When the machine is properly calibrated, the mean inflation pressure s
13.5 pounds, but uncontrollable factors can cause the pressure of individual dodge balls to
vary. For quality control purposes, the manufacturer wishes to estimate the mean inflation
pressure to within 0.025 pounds of its true value with a 99% confidence. What sample size
should be used?
A. 677
B. 107
C. 35
D. 27
E. 11 70. Recently, a case of food poisoning was traced to a particular restaurant chain. The source
was identified and corrective actions were taken to make sure that the food poisoning would
not reoccur. Despite the response from the restaurant chain, many consumers refused to visit
the restaurant for some time after the event. A survey was conducted three months after the
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 Construct a 95% confidence interval for the true proportion of the market who still
refuse to visit any of the restaurants in the chain three months after the event.
A. [.059 .122]
B. [.090 .091]
C. [.000 .196]
D. [.240 .339]
E. [.118 .244] 1630 Chapter 01  An Introduction to Business Statistics 71. Recently, a case of food poisoning was traced to a particular restaurant chain. The source
was identified and corrective actions were taken to make sure that the food poisoning would
not reoccur. Despite the response from the restaurant chain, many consumers refused to visit
the restaurant for some time after the event. A survey was conducted three months after...
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