1-20chapter stats

5 how many soil samples should be in our experiment a

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Unformatted text preview: 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. What sample size would be needed in order to be 99% confident that the sample proportion is within .02 of ρ, the true proportion of customers who refuse to go back to the restaurant? A. 14 B. 38 C. 129 D. 1,371 E. 1,777 72. In a survey of 308 adults, 17% listed jewelry among the romantic gifts men want to receive. Construct the 98% confidence interval for the proportion of all adults who include jewelry among their responses. A. [.025 .085] B. [.169 .171] C. [.120 .220] D. [.140 .200] E. [.050 .170] 73. In a poll of 1,004 adults, 93% indicated that restaurants and bars should refuse service to patrons who have had too much to drink. Construct the 90% confidence interval for the proportion of all adults who feel the same way. A. [.078 .108] B. [.914 .946] C. [.920 .940] D. [.917 .943] E. [.910 .950] 1-631 Chapter 01 - An Introduction to Business Statistics 74. At a sobriety checkpoint the sheriff's department screened 676 drivers and 6 were arrested for DWI. Find the 92% confidence interval for the true proportion of drivers who were DWI that evening. A. [0.000 0.027] B. [0.003 0.015] C. [0.902 0.938] D. [0.000 0.076] E. [0.006 0.030] 75. The Ohio Department of Agriculture tested 203 fuel samples across the state in 1999 for accuracy of the reported octane level. For premium grade, 14 out of 105 samples failed (they didn't meet ASTM specification and the FTC Octane posting rule). Find a 99% confidence interval for the true population proportion of premium grade fuel-quality failures. A. [.045 .221] B. [.068 .198] C. [.023 .115] D. [.047 .219] E. [.100 .276] 76. The Ohio Department of Agriculture tested 203 fuel samples across the state in 1999 for accuracy of the reported octane level. For premium grade, 14 out of 105 samples failed (they didn't meet ASTM specification and the FTC Octane posting rule). How many samples would be needed to create a 99% confidence interval that is within 0.02 of the true proportion of premium grade fuel-quality failures? A. 4148 B. 2838 C. 1913 D. 744 E. 54 1-632 Chapter 01 - An Introduction to Business Statistics 77. To investigate the rate at which employees with cancer are fired or laid off, a telephone survey was taken of 100 cancer survivors who worked while undergoing treatment. Seven (7) were either fired or laid off due to their illness. Construct a 90% confidence interval for the true percentage of all cancer patients who are fired or laid off due to their illness. A. [0.0000 0.2034] B. [0.0371 0.1029] C. [0.0039 0.1361] D. [0.0278 0.1122] E. [0.0078 0.1400] 78. In 1995, 13,000 WWW users were surveyed and asked about their willingness to pay fees for access to websites. Of these, 2,938 were definitely not willing to pay such fees. Construct a 95% confidence interval for the proportion definitely unwilling to pay fees. A. [0.286 0.302] B. [0.219 0.233] C. [0.220 0.232] D. [0.212 0.241] E. [0.214 0.245] 79. In 1995, 13,000 WWW users were surveyed and asked about their willingness to pay fees for access to websites. Of these, 2,938 were definitely not willing to pay such fees. How large a sample is necessary to estimate the proportion of interest to within 2% in a 95% confidence interval? A. 18 B. 307 C. 1717 D. 2000 E. 2965 80. In the construction of a confidence interval, as the confidence level required in estimating the mean increases, the width of the confidence interval ______________. A. Stays the same B. Decreases C. Increases 1-633 Chapter 01 - An Introduction to Business Statistics 81. As the sample size n increases, the width of the confidence interval _______________. A. Stays the same B. Decreases C. Increases 82. When establishing the confidence interval for the average weight of a cereal box, assume that the population standard deviation is known to be 2 ounces, and based on a sample the average weight of a sample of 20 boxes is 16 ounces. The appropriate test statistics to use is ________. A. t B. Z C. χ D. p 83. As the significance level, α increases, the width of the confidence interval _______________. A. Stays the same B. Decreases C. Increases 84. As the standard deviation, (σ) decreases, the width of the confidence interval _______________. A. Stays the same B. Decreases C. Increases 85. As the stated confidence level decreases, the width of the confidence interval _______________. A. Stays the same B. Decreases C. Increases 1-634 Chapter 01 - An Introduction to Business Statistics 86. As the margin of error decreases, the width of the confidence interval _______________. A. Stays the same B. Decreases C. Increases 87. If everything else is held constant, decreasing the margin of error, __________ the required sample size. A. Stays the same B. Decreases C. Increases 88. A confidence interval for the population mean is an interval constructed around the _____. A. Sample mean B. Population mean C. Z test statistic D. t test statistic 89. In determining the sample size to estimate...
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