If the candidate only wants a 2% margin of error at a 95% confidence level, what size of sample is needed? Give your answer in whole people.

Question

A political candidate has asked you to conduct a poll to determine what percentage of people support her.

If the candidate only wants a 2% margin of error at a 95% confidence level, what size of sample is needed?

Give your answer in whole people.

Answer 1

sample size = 0.25 * (z-critical/error)**2

error given as 0.02 and z-critical for 95% confidence level is z value for right tail alpha/2 (97.5)