pls help

An increasing number of Americans are moving to a warmer climate when they retire. To take advantage of this trend, Sunny Skies Unlimited is undertaking a major real-estate development project. The project is to develop a completely new retirement community (to be called Pilgrim Haven) that will cover several square miles. One of the decisions is where to locate the paramedic stations. At most 3 stations have been allocated to the community for medical emergencies. For planning purpose, Pilgrim Haven has been divided into five tracts, with no more than one paramedic station to be located in any given tract. Each station is to respond to all the medical emergencies that occur in the tract in which it is located as well as in the other tracts that are assigned to this station. Thus, the decision to be made consist of: (1) the tracts to receive a paramedic station and (2) the assignment of each of the other Tracts to one of the paramedic stations. The objective is to minimize the overall average of the response times to medical emergencies. The following table gives the average response time to a medical emergency in each Tract (rows) if that tract is served by a station in a given Tract (the columns). The last column gives the forecasted average number of medical emergencies that will occur in each of the tracts per day. Because of the limited resources, if the station(s) is located in Tracts 1 and 2 , only 1 tract can be served. If the station(s) is located in Tracts 3, 4, and 5, it can serve more than 1 tract. In addition, Tracts 3 and 4 can only have 1 station in a total. Formulate and solve a BIP model for this problem. Identify any constraints that correspond to mutually exclusive alternatives or contingent decisions