合肥AP培訓(xùn)班有沒(méi)有好的推薦？新東方教育科技集團(tuán)成立于1993年11月16日，現(xiàn)已發(fā)展成為一家集教育培訓(xùn)、教育研發(fā)、圖書(shū)雜志音像出版社、出國(guó)留學(xué)服務(wù)、職業(yè)教育、在線教育、教育軟件研發(fā)于一體的大型綜合性教育科技集團(tuán)，并于 2006在美國(guó)紐約證券交易所正式掛牌上市。

AP經(jīng)濟(jì)學(xué)重要概念：彈性

彈性是AP經(jīng)濟(jì)學(xué)考試考試的一個(gè)知識(shí)點(diǎn)，下面我用幾道題目來(lái)解釋一下這一章的知識(shí)要點(diǎn)。

1. Use the following diagram to answer the next question.

Refer to the diagram. Between the prices of $10 and $8, the price elasticity of demand is:

A) .5

B) .9

C) 1.11

D) 2

解釋?zhuān)何覀円獙W(xué)會(huì)用彈性公式中的中位法(middle point method) 來(lái)計(jì)算彈性，分子為數(shù)量變化，分母為價(jià)格變化。

(22 – 18) / 20 ÷ (10 – 8) / 9 = .9.

2. Use the following diagram to answer the next question.

Refer to the diagram. Suppose total revenue at price P3 is the same as at price P2. Then, over the price range from P2 to P3, demand is:

A) relatively elastic

B) relatively inelastic

C) unit elastic

D) perfectly elastic

解釋?zhuān)喝绻偸杖氩蛔?，需求變化和?shù)量變化一定保持一致，這是單位彈性(unit elasticity)

3. Suppose that a 2% increase in income in the economy decreases the quantity of gadgets demanded by 1% at every possible price. This implies that:

A) the supply of gadgets is elastic

B) income elasticity is positive and gadgets are a normal good

C) income elasticity is negative and gadgets are a normal good

D) income elasticity is negative and gadgets are an inferior good

解釋: 我們用需求的收入彈性公式計(jì)算income elasticity = –1/2 = –.5 如入增加，需求減少，商品是劣質(zhì)品(inferior good)

4. The maker of a particular breakfast cereal found that increasing the price from $4.00 to $4.25 per box had no impact on total revenue, but increasing the price further to $4.50 reduced total revenue by 2%. Thus, the demand for the cereal is:

A) inelastic over the range $4.00 to $4.50

B) elastic over the range $4.00 to $4.25 but not over the range $4.25 to $4.50

C) unit elastic over the range $4.00 to $4.25 and elastic over the range $4.25 to $4.50

D) unit elastic over the range $4.00 to $4.25 and inelastic over the range $4.25 to $4.50

解釋?zhuān)簝r(jià)格變化，收入不變，是單位彈性(unit elastic)。進(jìn)一步漲價(jià)，使得總收入下降2%， 說(shuō)明漲價(jià)對(duì)需求的影響很大，這個(gè)階段需求是富有彈性的(demand is elastic over this range)

5. A firm finds that its price elasticity of demand is 4.0. Currently, the firm is selling 2000 units per month at $5 per unit. If it wishes to increases its quantity sold by 10%, it must lower its price by:

A) $.40

B) $.50

C) 2.5%

D) 4.0%

解釋?zhuān)焊鶕?jù)彈性公式：數(shù)量變化量除以?xún)r(jià)格變化量等于彈性。 10%/ X= 4 X=2.5%