The mayor of a town has to decide how much of his budget to allocate to the fire department. As mayor you give the fire chief a simple goal: “protect us from fires!” The fire chief asks you: “Mayor, on average, how fast do you want fire department to respond to a fire?” The mayor needs to know the cost of each of the fire resistant methods outlined above. The mayor’s decision to make a budget decision, preferably with fire chief’s input, then let fire chief make the best resource allocation requested.”]
Source: https://taosecurity.blogspot.com/2010/03/time-and-cost-to-defend-town.html