What you’ll learn to do: construct a confidence interval and calculate the sample size needed for a given error bound for a population proportion

Each month a survey is done by a polling organization to estimate the approval rating of the current President of the United States. A poll such as this one will report a point estimate and a margin of error. Often the margin of error is plus or minus three percent. In this section you will learn how such margin of errors and confidence intervals are created for population proportions.