Exercise 19.19. Consider the steady-state world equilibrium in the model of Section 19.4. (1) Show that an increase in τ does not necessarily increase the steady-state world equilibrium growth rate g∗ as given by (19.37). Provide an intuition for this result. (2) Show that even when τ does not increase growth, it increases world welfare. [Hint: to simplify the answer to this part of the question, you can simply look at steady state welfare]. (3) Interpret this finding in light of the debate about the effect of trade on growth. (4) Provide a sufficient condition for an increase in τ to increase the world growth rate and interpret this condition.