Question 15 For this question a written answer is required. The city government is planning to allocate the fire stations in the city. There are totally 6 districts in the city, where each of them can have a fire station been built. The goal for the government is to allocate the minimum number of the fire stations while at the same time to satisfy the constraints that the fire truck can arrive at the spot within 15 mins if any fire happens in no matter what district in the city. The driving time between each district is shown in the table below, please help the government set up a plan to solve this problem. District 6 20 10 28 District5 27 17 27 10 21 District 1 District 2 District 3 District 4 District 1 16 District 2 10 0 24 32 District 3 1 6 24 0 12 District 4 28 12 0 District 5 27 17 District 6 20 10 Hint: you can use 0 and 1 to denote whether there is a fire station or not 32 15 25 27 15 14 0 14 21 25 0