f.4 econ 問題

Quantity demanded = It is that quantity that a person is willing and able to buy at a particular price level in a specific period of time.

Market Demand = It is the quanitity demanded at all price level. ( horizontally adding up the quantity demanded and so we can get the market demand )

** Do notes that when there is a change in price level of a good, there will be a movement along the Demand curve, when there is a change in factors other than change in price level ( i.e. taste/expectations), this will lead to a shift in demand curve to the left (fall in demand ) or to the right(rise in demand) .

It better for you to have a clear understanding abt these basic concepts first .. or else you'll be very confused in the future. For your question, taking a " Shortage" as an example, imagine there is a simple demand and supply curve digram, the equilibrium level will be at the intersaction point of demand and supply curve rite ?! It indicates the equilibrium price level and quantity demanded/transacted, where there is no further tendency for them to change.

However, if the price level has dropped below the equilibrium level, we can see that the Quanitity demanded is larger than Quantity supplied, where a shortage has occured. When you draw a horizontal line thru both curves at the new price level (below the equilibrium price level).. the quantity that price line and supply curve intersact are the quantity transacted.( The most that the market can supply). Furthermore, the quantity that the price line and demand intersact will be known as the quantity demanded, where consumer demand at this level, however, there is inadequate supply to satisfy them.

Recap : At equilibrium level. quantity demanded is just the same as quantity transacted.

* For econ, to my personal experience, no matter what question is being asked, put down the definitions of those main terms indicated in the question first, you can still gain copious marks for that even though you don't know how to answer ! And more, it is better to illustrate concepts with diagram, however, i don't know how to post up a diagram in here, i'm terribly sorry abt this and hope that you can get what i want to bring out above. Best of Luck ya !

2006-11-17 11:45:08 補充：
Quantity transacted; it's the exact quantity that have been bought/sold between sellers/buyers in the market no matter it is in situation of shortage/surplus/equilibrium.

quantity demanded 系個 market 要既數量。 一件商品應求既多少。
可以系供不應求 (例如低價高應求)﹐ 供過於求 (例如太多人賣﹑ 買者付擔不起的)﹐ 或者系 equilibrium 供等於求。 一個可以改變既數字﹐ 可以由供過於求或供不應求變成供等於求﹐ 改變個 supply﹐ 改變個價錢﹐ 改變經濟﹐ 之類。

quantity transacted 系個已經交易左既數量﹐ 有加無減。 當你賣左甘多甘多﹐ 你無可能要人退回產品等你可以用減法。