Question

Estimate how many people you'd need to poll to get a 95% confidence interval with a margin of error of 2%

Answer 1

Here, the confodence level is 95%. We know, z value for 95% CI = 1.96 ( from z critical value table)

MOE = 2% = 0.02

Here , the sample proportion, is not given , so we take   = 0.5.

The required sample size is = (z / MOE)2 *   * (1- )

= 9604 * 0.5 * 0.5

= 2401

The required number of people is 2401.