Let [math]X[/math] be a random variable with density function [math]f_X[/math]. The mean of [math]X[/math] is the value [math]\mu = \int xf_x(x)\,dx[/math]. Then [math]\mu[/math] gives an average value for [math]X[/math] (see Section \ref{sec 6.3}). Find [math]\mu[/math] if [math]X[/math] is distributed uniformly, normally, or exponentially, as in Exercise.