suppose-a-researcher-wants-to-estimate-the-proportion-of-potential-voters-who-support-a-law-that-forbids-smoking-in-public-with-a-margin-of-error-of-3-how-many-potential-voters-must-be-surveyed-if-we-want-a-95-confidence-interval

Suppose a researcher wants to estimate the proportion of potential voters who support a law that forbids smoking in public, with a margin of error of 3%. How many potential voters must be surveyed if we want a 95% confidence interval?