Given that the population standard deviation is 3.7, what sample size is required to be 95% confident that the estimated mean has an error less than 0.05?

OPTIONS

• 783
• 42074
• 21037
• 412

ANSWER

21037

EXPLANATION

If the sample average is used to estimate the population mean, the confidence that the error will not exceed E is (1-alpha). The same size is computed by the expression: n = Z2sigma2 / E2 n = (1.96)2 * (3.7)2/(0.05)2 n = 21037