20. Let X be an RV such that log (X - a) is N(p, o'). Show that X has PDF log(x - a) - /]] exp if x >a, f(x) = o(x -a)v2x 202 if x Ca. If my, my are the first two moments of this distribution and a3 = (3/m, is the coefficient of skewness, show that a, /t, o are given by 1712 - 1717 ' = log(1 + 17). and p = log (mm] - a) - 5 where r is the real root of the equation ,' + 37 -03 =0