You may need to use the appropriate appendix table or technology to answer this question. A simple random sample of 50 items resulted in a sample mean of 25. The population standard deviation is = 9. (Round your answers to two decimal places.) (a) What is the standard error of the mean, -? (b) At 95% confidence, what is the margin of error? You may need to use the appropriate appendix table or technology to answer this question. For a t distribution with 19 degrees of freedom, find the area, or probability, in each region. (Round your answers to three decimal places.) (a) to the right of 1.729 0.050 (b) to the left of 1.328 0.90004 (c) to the left of -2.539 0.010 (d) to the right of 2.093 0.025 (e) between -1.729 and 1.729 0.05 (f) between -2.539 and 2.539 0.980 You may need to use the appropriate appendix table or technology to answer this question. Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $42,000 and $55,400. Assume that a 95% confidence interval estimate of the population mean annual starting salary is desired. (Round your answers up to the nearest whole number.) What is the planning value for the population standard deviation? 1.96 (a) How large a sample should be taken if the desired margin of error is $500? 333 (b) How large a sample should be taken if the desired margin of error is $200? 1078 (c) How large a sample should be taken if the desired margin of error is $100? 8307 (d) Would you recommend trying to obtain the $100 margin of error? Explain. No, the sample size would probably be too time consuming and costly. You may need to use the appropriate appendix table or technology to answer this question. Fewer young people are driving. In year A, 65.9% of people under 20 years old who were eligible had a driver's license. Twenty years later in year B that percentage had dropped to 43.7%. Suppose these results are based on a random sample of 1,600 people under 20 years old who were eligible to have a driver's license in year A and again in year B. (a) At 95% confidence, what is the margin of error of the number of eligible people under 20 years old who had a driver's license in year A? (Round your answer to four decimal places.) At 95% confidence, what is the interval estimate of the number of eligible people under 20 years old who had a driver's license in year A? (Round your answers to four decimal places.) to (b) At 95% confidence, what is the margin of error of the number of eligible people under 20 years old who had a driver's license in year B? (Round your answer to four decimal places.) At 95% confidence, what is the interval estimate of the number of eligible people under 20 years old who had a driver's license in year B? (Round your answers to four decimal places.) to (c) Is the margin of error the same in parts (a) and (b)? Why or why not? The margin of error in part (a) is ---Select--- than the margin of error in part (b). This is because the sample proportion of eligible people under 20 years old who had a driver's license in year B is ---Select--- than the sample proportion of eligible people under 20 years old who had a driver's license in year A. This leads to a ---Select--- interval estimate in part (b). You may need to use the appropriate appendix table or technology to answer this question. A simple random sample of 400 individuals provides 140 Yes responses. (a) What is the point estimate of the proportion of the population that would provide Yes responses? 0.35 (b) What is your estimate of the standard error of the proportion, -? (Round your answer to four decimal places.) ? 0.0240 (c) Compute the 95% confidence interval for the population proportion. (Round your answers to four decimal places.) 0.3033 to 0.3967