SECTION 6.3 Confidence Intervals for Population Proportions 327 21. In Exercise 11, would it be unusual for the population proportion to be 72.5%? Explain. 22. In Exercise 12, would it be unusual for the population proportion to be 48%? Explain. 23. In Exercise 17(b), would a sample size of 400 be acceptable? Explain. 24. In Exercise 18(b), would a sample size of 5000 be acceptable? Explain. Constructing Confidence Intervals In Exercises 25 and 26, use the figure, which shows the results of a survey in which 1051 adults from France, 1042 adults from Germany, 1003 adults from the United Kingdom, and 1000 adults from the United States were asked whether national identity is strongly tied to birthplace. (Source: Pew Research Center) National Identity and Birthplace France Germany United Kingdom United States 32% 25% 31% 35% identity is strongly tied to birthplace People from different countries who believe national 25. National Identity Construct a 99% confidence interval for the population proportion of adults who say national identity is strongly tied to birthplace for each country listed. 26. In Exercise 25, which two countries are the least likely to have equal population proportions? Explain. Constructing Confidence Intervals In Exercises 27 and 28, use the figure, which shows the results of a survey in which 1021 U.S. adults were asked whether they see each of the possible threats to the vital interests of the United States as a critical threat in the next 10 years. (Source: Gallup) Percent of U.S. adults who see each as a critical threat Critical Threats to the U.S. Development of nuclear weapons by Iran The spread of infectious diseases throughout the world Global warming or climate change The military power of Russia The conflict between the Israelis and the Palestinians 75% 72% 58% 44% 32% Cyberterrorism, the use of computers to cause disruption or fear in society 82% 27. Critical Threats Construct a 95% confidence interval for the population proportion of U.S. adults who gave each response. 28. In Exercise 27, which two threats are the most likely to have equal population proportions? Explain.
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