In the original Western set-covering model in Figure 6.15, we used the number of hubs as the objective to minimize. Suppose instead that there is a fixed cost of locating a hub in any city, where...

In the original Western set-covering model in Figure 6.15, we used the number of hubs as the objective to minimize. Suppose instead that there is a fixed cost of locating a hub in any city, where these fixed costs can possibly vary across cities. Make up some reasonable fixed costs, modify the model appropriately, and use Solver to find the solution that minimizes the sum of fixed costs.