A pollster wants to construct a 95% confidence interval for the proportion of ad

Question

A pollster wants to construct a 95% confidence interval for the proportion of adults who believe that economic conditions are getting better. A Gallup poll taken in July 2010 estimates this proportion to be 0.33. Using this estimate, what sample size is needed so that the confidence interval will have a margin of error of 0.066? Write only an integer as your answer. Your Answer: A pollster wants to construct a 95% confidence interval for the proportion of children who watch Spongebob Squarepants. Estimate the sample size needed so that the confidence interval will have a margin of error of 0.037. Write only an integer as your answer. Your Answer:

Explanation / Answer

(11) z score for 95% confidence is z = 1.96

E = 0.066

p = 0.33, q = 1 - p = 0.67

N = (z/E)^2 * pq

N = (1.96/0.066)^2 * 0.33 * 0.67 = 195

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