Thank you for the help, I appreciate it :)

Health insurers and the federal government are both putting pressure on hospitals to shorten the length of stay (LOS) of their patients. A random sample of 24 hospitals in Pennsylvania was selected, and the mean LOS for each hospital was measured. (Assume the length of stay is normally distributed.) A 90% confidence interval for the population mean of the LOS in Pennsylvania is given by (3.65, 4.56) days. a. What is the value of the sample mean from these data? b. Determine the 99% confidence interval for the population mean of the LOS in Pennsylvania. c. Suppose the population mean of the LOS in Pennsylvania hospitals was 4.9 days in 2001. Does your answer from (b) suggest that the mean LOS has changed in the last twenty years? Why or why not