a pollster wants to construct a 95% confidence interval for the proportion of adults who believe the economic conditions are getting better.

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a pollster wants to construct a 95% confidence interval for the proportion of adults who believe the economic conditions are getting better. A gallup poll taken in July 2010 estimates this proportion to be 0.33. Using this proportion what sample size is needed so that the confidence interval will have a margin of error of 0.015?