Confidence Intervals for Population Proportion: Videos & Practice Problems

A researcher plans to estimate the percentage of U.S. adults who believe that organic food is healthier. Based on a previous survey, $40\%$ of respondents believed in the health benefits of organic food. The researcher wants a $99\%$ confidence level and a margin of error of $3$ percentage points. How many people must be surveyed to estimate the percentage of adults who believe organic food is healthier?