3.4 Functions of random variables. Assume that the locations of an incident and a response unit are independently, uniformly distributed over a rectangle with dimensions X_{0}, Y_{0} (see Exercise 3.1). The sides of the rectangle are defined parallel to directions of travel. If the incident and response unit locations are (X_{1}, Y_{1}) and (X_{2}, Y_{2}), respectively, the travel distance is D = X_{1}  X_{2} + Y_{1}  Y_{2}
