statistics
posted by Panther on .
An economist wants to estimate the mean income for the first year of work for college
graduates who majored in biology. How many such incomes must be found if the
economist wants to be 95% confident that the sample mean is within $500 of the true
population mean? Assume that research has found that the population standard
deviation for such incomes is equal to $6,250.

95% = mean ± 1.96 SEm
1.96 SEm = $500
SEm = SD/√n