text: i have 3685 people, how many must i survey for a representative response (95%) to a question?   zero.  i'm being a jerk, but for an important reason.  your question is incomplete.  you can ask two people and have a 95% confidence that the results are representative.  but your margin of error is 75 percent.  that's the part i'm being a jerk about.  if you're trying to predict an election, 3 or 5% is probably close enough.  but that means a 55 to 45 vote is as likely as a 45 to 55 vote.    and 3% means asking more than 800 people, 5% only 350.  if you sell extended computer warranties and need to know how often their pc breaks, a smaller error is very important.  you can use an online tool to calculate these figures [click below] or you can skip the audi tt and go to graduate school to learn how to do it yourself [damn! there was an online tool?].  but this is only an estimate.  the actual figures depend on the question and consistency of the answers.