AU outreach office wishes to investigate the mean first year of employment salaries after graduation for AU graduates. They want...

AU outreach office wishes to investigate the mean first year of employment salaries after graduation for AU graduates. They want the interval to have a margin of error of $500 or less with 90% confidence level. The standard deviation of this distribution is known to be $9750. How large of a sample will the researcher need, and why do we always round up the sample size? (1pt)