Create a mathametical model for the variable Z in the following: Let X be a uniform random variable with support Rx = (0, 1] and probability density function: for r Rx, S(z) = otherwise. and Y an exponential random variable, independent of X, with support Ry = [0, o0] and probability density function: (exp(-y) S(u) = lo for y E Ry, otherwise. Derive the probability density function of the sum Z = X +Y