27. 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. What is the planning value for the population standard deviation? How large a sample should be taken if the desired margin of error is

a. $500?

b. $200?

c. $100?

d. Would you recommend trying to obtain the $100 margin of error? Explain.