Annual starting salaries for college graduates with degrees

Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $30,000 and $45,000. Assume that a 95% confidence interval estimate of the population mean annual starting salary is desired. How large a sample should be taken if the desired margin of error is.

a.) $500

b.) $200

c.)$100

Solution

planning value = (45000-30000)/4 = 15000/4 = 3750

a. $500?
n = (Za/2* /E)^2
n = (1.96* 3750/500)^2
n = 217


b. $200?
n = (Za/2* /E)^2
n = (1.96*3750/200)^2
n = 1351


c. $100?
n = (Za/2* /E)^2
n = (1.96* 3750/100)^2
n = 5403