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

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 7% margin of error at a 95% confidence level, what size of sample is needed?

Give your answer in whole people.

Answer 1

n = p(1-p) * (z-critical/MOE)^2

since estimate of population proportion not given, use p = 0.5

MOE = 7% = 0.07. z-critical = 1.96

n = (0.25)*(1.96/0.07)^2 = 196