Let X_1,X_2,......,X_n be a random sample from an arbitrary and continuous distribution with cumulative distribution function F(x- \theta). Let p_1 = P(X_1 > 0), p_2 = P(X_1 + X_2> 0), p_3 = P(X_1 + X_2> 0, X_1 > 0). Show that, when then the population is symmetric at zero and is continunous, P_3 = 3/8