O Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $20,000 and $35,000. Assume that a 95% confidence interval estimate of the population mean annual starting salary is desired. O a. What is the planning value for the population standard deviation? O 3750 b. How large a sample should be taken if the desired margin of error is $400? Round your answers to next whole number. O $270? $130? c. Would you recommend trying to obtain the $130 margin of error? Explain