Question $4$: Consider the location decision problem discussed in class where the decision

maker wanted to identify the minimum number of service facility in the following figure.

FIGURE $7\mathrm{.}9$ THE $20-$COUNTY RERION INI NIDTHEACTEDN OUIO

$(4\mathrm{.}1)$ Develop an alternative method to represent the data shown in the above map that

can show the neighborhood of the twenty counties efficiently and then formulate an

optimization model to determine the minimum number of service facility.

Hint: A matrix can be defined to present the neighbourhood.

$(4\mathrm{.}2)$ Solve the model by Solver and obtain an optimal solution.