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Statistic Scenarios

Gun Violence. The Harris Poll asked a sample of 1009 adults which causes of death they thought would become more common in the future. Gun violence topped the list; 706 members of the sample thought deaths from guns would increase. Although the samples in national polls are not SRSs, they are similar enough that our method gives approximately correct confidence intervals.

(a) Say in words what the population proportion p is for this poll
(b) Find a 95% confidence interval for p
(c) Harris announced a margin of error of plus or minus three percentage points for this poll result. How well does your work in (b) agree with this margin of error?

4.2

Attending church. Although opinion polls have long found that about 40% of American adults say they attended religious services last week, this is almost certainly not true.

(a) Why might we expect answers to a poll to overstate true church attendance?
(b) You suspect strongly that the true percentage attending church in any given week is less than 40%. You plan to watch a random sample of adults and see whether or not they go to church. What are your null and alternative hypotheses? (Be sure to say in words what the population proportion p is for your study.)

Solution Preview

(a) Say in words what the population proportion p is for this poll
The population proportion for this poll will be close to p = 706/1009 = 0.6997

(b) Confidence interval - ...

Solution Summary

Gun Violence. The Harris Poll asked a sample of 1009 adults which causes of death they thought would become more common in the future. Gun violence topped the list; 706 members of the sample thought deaths from guns would increase. Although the samples in national polls are not SRSs, they are similar enough that our method gives approximately correct confidence intervals.

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