【正文】 2020 Pearson AddisonWesley Decrease in Demand and Increase in Supply A decrease in demand and an increase in supply lowers the equilibrium price. The change in equilibrium quantity is uncertain because the decrease in demand decreases the equilibrium quantity and the increase in supply increases it. Predicting Changes in Price and Quantity 169。 2020 Pearson AddisonWesley Increase in Both Demand and Supply An increase in demand and an increase in supply increase the equilibrium quantity. The change in equilibrium price is uncertain because the increase in demand raises the equilibrium price and the increase in supply lowers it. Predicting Changes in Price and Quantity 169。 2020 Pearson AddisonWesley Change in Supply with No Change in Demand When supply increases, there is a movement down along the demand curve. The equilibrium price falls and the equilibrium quantity increases. Predicting Changes in Price and Quantity 169。 2020 Pearson AddisonWesley Change in Demand with No Change in Supply When demand increases, there is a movement up along the supply curve. The equilibrium price rises and the equilibrium quantity increases. Predicting Changes in Price and Quantity 169。 2020 Pearson AddisonWesley An Increase in Supply Figure shows that when supply increases the supply curve shifts rightward. At the original price, there is now a surplus. The price falls, and the quantity demanded increases along the demand curve. Predicting Changes in Price and Quantity 169。 2020 Pearson AddisonWesley Price Adjustments At any price above the equilibrium price, a surplus forces the price down. At any price below the equilibrium price, a shortage forces the price up. At the equilibrium price, buyers’ plans and sellers’ plans agree and the price doesn’t change until some event changes either demand or supply. Market Equilibrium 169。 2020 Pearson AddisonWesley Price as a Regulator Figure illustrates the equilibrium price and equilibrium quantity. If the price is $ a bar, the quantity supplied exceeds the quantity demanded. There is a surplus of 6 million energy bars. Market Equilibrium 169。 2020 Pearson AddisonWesley A Shift of the Supply Curve If the price remains the same but some other influence on sellers’ plans changes, supply changes and the supply curve shifts. Supply 169。 2020 Pearson AddisonWesley A Change in the Quantity Supplied Versus a Change in Supply Figure illustrates the distinction between a change in supply and a change in the quantity supplied. Supply 169。 2020 Pearson AddisonWesley Technology Advances in technology create new products and lower the cost of producing existing products. So advances in technology increase supply and shift the supply curve rightward. The State of Nature The state of nature includes all the natural forces that influence production— for example, the weather. A natural disaster decreases supply and shifts the supply curve leftward. Supply 169。 2020 Pears