a civil engineer is studying the live loads on a highway bridge. let y and z denote the live load (in ten thousands of pounds) for traffic going east and west, respectively, at a randomly selected time of day. suppose these random variables have a joint distribution with density function f(y,z) = (1/400)yz^2e^(–y/5–z/2), for y > 0, z > 0.
What type of distributions do Y and Z have? Use this to confirm the mean and standard deviation of each variable.
