X1, X2, X3 are three random variable with uniform distribution at [0 1]. Solve the PDF of Z=X1+X2+X3.
The Attempt at a Solution
PDF of Z, f_z=[tex]\int[/tex][tex]\int[/tex]f_x1(z-x2-x3)*f_x2*f_x3 dx2 dx3
I saw the answer at http://eom.springer.de/U/u095240.htm, but I cannot figure out how to get there...please help.