Using a 95 percent confidence interval, a researcher reports that 48 percent to 52 percent and 52 percent reflects the Multiple Choice confidence values. sampling error. census limits. sample size.
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STAT 1040 Activity 9B 1. Which of the following confidence intervals will be the widest? a. 90 percent b. 95 percent c. 80 percent d. 98 percent 2. Narrower confidence intervals are considered more accurate. Which of the following actions would increase the accuracy of a confidence interval? Check all that apply. a. Increase the sample size. b. Decrease the sample size. c. Increase the confidence level. d. Decrease the confidence level. 3. A health center noted that in a simple random sample of 600 patients, 120 were referred to them by the local hospital. The sample percentage is _____ and the SE% is _____. (Round answers to 1 decimal place. Only enter numbers into the blanks.) 4. A health center noted that in a simple random sample of 600 patients, 120 were referred to them by the local hospital. An approximate 90% confidence interval for the percentage of health center patients who were referred by the hospital is: a. 17.31% to 22.69% b. 13.4% to 26.6% c. 16.73% to 23.27% d. 15.10% to 24.90% 5. On September 2, 2004, a Dan Jones poll based on a random sample of 408 Salt Lake County residents reported that 26% of the respondents thought that Mayor Nancy Workman should resign. A 95% confidence interval for the percent of all residents in Salt Lake County that felt Nancy Workman should resign is: a. 21.6% to 30.4% b. 25.8% to 26.2% c. 70% to 78% d. 17.4% to 35.6% 6. A candy company is market-testing a new brand of chocolate bar. A simple random sample of 400 people were given the new chocolate bar to try. A total of 285 said they liked the candy. A 98% confidence interval for the population percentage of people who will like the new chocolate bar is: a. 71.3% to 98.0% b. 66.0% to 76.5% c. 67.5% to 75.0% d. 70.0% to 76.6% 7. Marketing executives at a dairy company gave a new flavor of yogurt to a focus group of 385 randomly selected people. Based on the number of people who said they liked it, they calculated a 90% confidence interval for the true percentage of customers who will like the yogurt to be 35.8% to 44.1%. Choose the statement that is TRUE. a. The company can reasonably believe that at least 50% of consumers who try the new yogurt will like it. b. About 90% of people will say they like the new yogurt between 35.8% and 44.1% of the time. c. The company can be 90% confident that the true percentage of consumers who will like their new yogurt is between 35.8% and 44.1%. d. There is a 90% chance that the sample percentage of people who will say they like the new yogurt will be between 35.8% and 44.1% if we take another simple random sample of 385 people.
Adi S.
Which of the following would be a correct interpretation of a 99% confidence interval such as 4.1 < μ < 5.6? Choose the correct answer below. A. We are 99% confident that the interval from 4.1 to 5.6 actually does contain the true value of μ. B. There is a 99% chance that μ will fall between 4.1 and 5.6. C. It means that 99% of sample means fall between 4.1 and 5.6. D. It means that 99% of all data values are between 4.1 and 5.6. An IQ test is designed so that the mean is 100 and the standard deviation is 12 for the population of normal adults. Find the sample size necessary to estimate the mean IQ score of statistics students such that it can be said with 95% confidence that the sample mean is within 3 IQ points of the true mean. Assume that σ = 12 and determine the required sample size using technology. Then determine if this is a reasonable sample size for a real world calculation. The required sample size is _______. (Round up to the nearest integer.) Would it be reasonable to sample this number of students? No. This number of IQ test scores is a fairly small number. Yes. This number of IQ test scores is a fairly small number. Yes. This number of IQ test scores is a fairly large number. No. This number of IQ test scores is a fairly large number. A newspaper provided a "snapshot" illustrating poll results from 1910 professionals who interview job applicants. The illustration showed that 26% of them said the biggest interview turnoff is that the applicant did not make an effort to learn about the job or the company. The margin of error was given as ± 3 percentage points. What important feature of the poll was omitted? Choose the correct answer. The confidence level The sample size The point estimate The confidence interval
Jason G.
18. The criterion for using the normal distribution to approximate the sampling distribution of the sample proportion is a. n ≥ 30 b. n*π ≥ 5 and n*(1-π) ≥ 5 c. Either of the above d. Both of the above 19. A 98% confidence interval estimate for a population mean μ is determined to be 75.38 to 86.52. If the confidence level is reduced to 90%, the confidence interval for μ a. becomes wider b. remains the same c. becomes narrower d. None of the above. 20. To estimate with 99% confidence the mean of a normal population, whose standard deviation is assumed to be 6 and the maximum allowable sampling error is assumed to be 1.2, requires a random sample of size a. 166 b. 165 c. 164 d. 163 21. Under which of the following circumstances is it impossible to construct a confidence interval for the population mean? a. A non-normal population with a large sample and an unknown population variance b. A normal population with a large sample and a known population variance c. Non-normal population with a small sample and an unknown population variance d. A normal population with a small sample and an unknown population variance 22. A confidence interval was used to estimate the proportion of international students. A random sample of 72 students generated the following 90% confidence interval: (0.438, 0.642). Using the information above, what size sample would be necessary if we wanted to estimate the true proportion to within ± 0.08 using 95% confidence? a. 105 b. 150 c. 420 d. 597.
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