Margins of Error and Confidence Intervals. For each sample described below, calculate the margin of error (round to 3 decimal places) and the 95% confidence interval. 7) Sample size = 200, sample proportion = .35 [2 points] 8) Sample size = 36, sample proportion = .72 [2 points] 9) "Average" Drivers. For many years I have had my PSY1010 students answer a page of questions at the beginning of the semester. Of the 1,457 polled to date, 881 described themselves as "average" drivers. a) Calculate the sample proportion (round to 2 decimal places). [.5 point] b) Calculate the margin of error (round to 3 decimal places) and 95% confidence interval. [2 points] 10) Retrospective Approval. A recent Gallup poll of 1,013 US adults asked them to reflect on the performance of past presidents. It found that only 321 of them approved of the job that Richard Nixon did as President. a) Calculate the sample proportion (round to 2 decimal places). [.5 point] b) Calculate the margin of error (round to 3 decimal places) and 95% confidence interval. [2 points]
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So, 35/200 = 0.175. The formula for the margin of error is \(Z*\sqrt{\frac{p(1-p)}{n}}\), where Z is the Z-score (for a 95% confidence interval, Z = 1.96), p is the sample proportion, and n is the sample size. So, the margin of error is Show more…
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