4. For each case below, draw a separate graph. In each case first draw the initial equilibrium in the market and identify equilibrium price (P*) and quantity (Q*). Then shift either the supply or the demand curve so that P* and Q* change as indicated. Think of reasons in each case that would lead to such a change in the equilibrium. Indicate whether the change you have identified is a change in demand or supply. (a) market for potatoes: P* Q* (b) market for automobiles: P* Q* (c) market for grapefruits: P* Q* (d) market for personal computers: P* Q*