What is formula for calculating sample size of a specific population to obtain a confidence level?

Answer 1

n = [((Za/2)sigma)/E]2

n = sample size

(Za/2) = critical value

sigma = population standard deviation

E = margin of error

This formula can be used when you know sigma and want to determine the necessary sample size to establish, within a confidence of 1-a, the population mean to within +-E.

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