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Statistics Questions




Question;8.27 If n = 400 and X = 25;construct a 99% confidence interval estimation for the population proportion.;8.37 If you want to be 95% confident of estimating the population proportion to;within a sampling error of ?0.02 and there is historical evidence that the;population proportion is approximately 0.40, what sample size is needed?;9.16 The manager of a paint supply store wants to determine whether the mean;amount of paint contained in 1-gallon cans purchased from a nationally known;manufacturer is actually 1 gallon. you know from the manufacturer's;specifications that the standard deviation of the amount of paint is 0.02;gallon. you select a random sample of 50 cans and the mean amount of paint per;1-gallon can is 0.995 gallon.;a, is there evidence that the mean amount is different from 1.0 gallon(use;=0..01)?;b, compute the p-value and interpret its meaning.;c, Construct a 99% confidence interval estimate of the population mean amount;of paint.;d, Compare the result of (a) and (c). What conclusions do you reach?;9.17 Suppose that in Problem 9.16, the standard deviation is 0.012 gallon.;a. Repeat (a) through (d) of Problem 9.16, assuming a standard deviation of;0.012 gallon.;9.27 The U.S. Department of Transportation requires tire manufacturers to provide performance information on tire sidewalls to help prospective buyers make their purchasing decisions. One very important piece of information is the tread wear index, which indicates the tires resistance;to tread wear. A tire with a grade of 200 should last twice as long, on average, as a tire with a grade of 100. A consumer organization wants to test the actual tread Wear index of a brand name of tires that claims ?graded 200? on the sidewall of the tire. A random sample of indicates a sample mean tread wear index of 195.3 and a sample standard deviation of 21.4.;A). Is there evidence that the population mean tread wear index;is different from 200? (Use a 0.05 level of significance.);9.49 You are the manager of a restaurant that delivers pizza to college;dormitory rooms. You have just changed your delivery process in an effort to;reduce the mean time between the order and completion of delivery from the;current 25 minutes. A sample of 36 orders using the new delivery process yields;a sample mean of 22.4 minutes and a sample standard deviation of 6 minutes.;A) Using the six-step critical value approach, at the 0.05 level of;significance, is there evidence that the population mean delivery time has been;reduced below the previous population mean value of 25 minutes?;9.57 One of the issues facing organizations is increasing diversity throughout;the organization. One of the ways to evaluate an organization?s success at;increasing diversity is to compare the percentage of employees in the;organization in a particular position with a specific background to the;percentage in a particular position with that specific background in the;general workforce. Recently, a large academic medical center determined that 9;out of 17 employees in a particular position were females whereas 55% of the;employees for this position in the general workforce were females. At the 0.05;level of significance, is there evidence that the proportion of females in this;position at this medical center is different from what would be expected in the;general workforce?


Paper#60410 | Written in 18-Jul-2015

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