The mean was equal tothe standard deviation of the population, o, divided by the square root of the sample size, n: SE =_ (population standard deviation known) N Population Minimum Maximum Mean Std. Deviation X9 = Total Flight Time 306 11.7 35000.0 6185.339 5836.1251 Valid N (listwise) 306 Because we do not know o, we can use the standard deviation of the sample as an approximation for o to determine the standard error of the mean. SE =! SD Vn (population standard deviation unknown). Question: Calculate SE