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From 1. a population with a variance of 900, a sample of 225 items is selected. At 95% confidence, the margin of error is a. 2 b. 15 >>c. 3.92 d. 4 2. In order to determine an interval for the mean of a population with unknown standard deviation a sample of 61 items is selected. The mean of the sample is determined to be 23. The number of degrees of freedom for reading the t value is a. 22 b. 61 c. 23 >>d. 60 3. If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is a. 0.485 b. 1.96 >>c. 0.95 d. 1.645 4. As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution a. stays the same b. becomes larger >>c. becomes smaller d. None of these alternatives is correct. 5. The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the a. interval estimate b. parameter estimate c. confidence level >>d. margin of error 6. The z value for a 97.8% confidence interval estimation is a. 1.96 >>b. 2.29 c. 2.00 d. 2.02 7. The t value for a 95% confidence interval estimation with 24 degrees of freedom is >>a. 2.064 b. 1.711 c. 2.069 d. 2.492 8. As the sample size increases, the margin of error >>a. decreases b. stays the same c. increases d. increases or decreases depending on the of size the mean 9. A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to 0.90, the interval for a. does not change b. becomes wider c. becomes 0.1 >>d. becomes narrower 10. If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect >>a. the size of the confidence interval to increase b. the size of the confidence interval to remain the same c. the sample size to increase d. the size of the confidence interval to decrease 11. In general, higher confidence levels provide a. unbiased estimates b. a smaller standard error >>c. wider confidence intervals d. narrower confidence intervals 12. A sample of 225 elements from a population with a standard deviation of 75 is selected. The sample mean is 180. The 95% confidence interval for is >>a. 170.2 to 189.8 b. 175.0 to 185.0 c. 105.0 to 225.0 d. 100.0 to 200.0 13. A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mean is a. 15.2 to 24.8 b. 19.216 to 20.784 >>c. 19.200 to 20.800 d. 21.2 to 22.8 14. It is known that the population variance equals 484. With a 0.95 probability, the sample size that needs to be taken if the desired margin of error is 5 or less is a. 25 b. 189 >>c. 75 d. 74 ... View Full Document