The file P2_17.XLS reports the number of short-term general hospitals in each of a large number of U.S. metropolitan areas. Suppose that you are a sales manager for a major pharmaceutical producer and are interested in estimating the average number of such hospitals in all metropolitan areas across the entire country. Assuming that you do not have access to the data for each metropolitan location, you decide to select a sample that will be representative of all such areas. 

a. Choose a simple random sample of 30 metropolitan areas from the given frame. Compute the mean number of short-term general hospitals for the metropolitan areas included in your sample. 

b. Do you believe that simple random sampling is the best approach to obtaining a representative subset of the metropolitan areas in the given frame? Explain. If not, how might you proceed to select a better sample of size 30 using the data provided in P2_17.XLS? Compute the mean number of short-term general hospitals for the metropolitan areas included in your revised sample. How does this sample mean compare to that computed from your simple random sample in part a?