Question

In: Statistics and Probability

A researcher wishes to​ estimate, with 90​% confidence, the population proportion of adults who think Congress...

A researcher wishes to​ estimate, with 90​% confidence, the population proportion of adults who think Congress is doing a good or excellent job. Her estimate must be accurate within

22​% of the true proportion.

​(a) No preliminary estimate is available. Find the minimum sample size needed.

​(b) Find the minimum sample size​ needed, using a prior study that found that 20​%

of the respondents said they think Congress is doing a good or excellent job.

​(c) Compare the results from parts​ (a) and​ (b).

Solutions

Expert Solution

A researcher wishes to estimate with 90% confidence, the population proportion of adults who think Congress is doing good or excellent job. Her estimate must be accurate within 22% of the true proportion.

That is margin of error of me=0.22

The minimum sample size needed:


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