•Effect of law enforcement on city crime level
•"If a city is randomly chosen and given ten additional police officers, by how much would its crime rate fall?"
•Alternatively: "If two cities are the same in all respects, except that city A has ten m

It is difficult to answer this question without having specific data related to the chosen city and its crime rate. Generally speaking, the effect of law enforcement on a city's crime rate can vary significantly depending on a variety of factors including the size of the city, the types of crime being monitored, the resources of the law enforcement agency, and other local and regional conditions. Increasing the number of police officers could result in a decrease in crime, or it could have little effect. Therefore, without data from the city or an analysis of the local environment, it is impossible to determine the effect that adding ten additional police officers will have on the city's crime rate.