In part 2 of the question the mean residual life is given as 1 for the Exp(1) dist and for Ga(2,1) it is 1 + 1/(x+1) I understand that the exp dist is constant for the mean residual life And for gamma it is a decreasing function of x however I don’t understand why in this particular instance the solution says that the Ga distribution has a lighter tail than the exp dist the mean residual life will decrease asymptotically towards 1 so it’s always above the mean residual life for Exp(1) dist surely this mean that the Ga distribution has a heavier tail??
You are absolutely right. Thanks very much for raising this. We'll add it to the CS2 corrections document.