A Medical Records Manager Would Like to Review Hospital Records $\text { σ }$

Short Answer

A medical records manager would like to review hospital records in order to determine the average hospital stay for surgery patients during the past year.What sample size must be taken in order to be 95% confident that the estimate is within 1 day of the true mean? She has past studies,which indicate that $\text { σ }$
is 20.25 days.