Reconsider Problem 7.11. The management of Sunny Skies Unlimited now has decided that the decision regarding the locations of the paramedic stations should be based mainly on costs. The cost of locating a paramedic station in a tract is $200,000 for tract 1, $250,000 for tract 2, $400,000 for tract 3, $300,000 for tract 4, and $500,000 for tract 5. Management’s objective now is to determine which tracts should receive a station to minimize the total cost of stations while ensuring that each tract has at least one station close enough to respond to a medical emergency in no more than 15 minutes. In contrast to the original problem, note that the total number of paramedic stations is no longer fixed. Furthermore, if a tract without a station has more than one station within 15 minutes, it is no longer necessary to assign this tract to just one of these stations. Formulate the algebraic form of a pure BIP model with five binary variables for this problem. Display and solve this model on a spreadsheet.