作者generalman (筋肉人二世将军人)
看板Economics
标题[考试] 电浆电视的弧弹性绝对值大於1，算需求量
时间Mon Feb 27 19:33:06 2012
来源: 93学年度技术学院专业科目(一) 管理类(二)管理类(四) 经济学
科目:经济学
问题:
假设某型电浆电视为正常财，消费者对其需求的弧弹性之绝对值大於1，当价格由每台20
万元降为15万元时，需求量会如何变动?
(A)增加，幅度小於14%
(B)减少，幅度大於28%
(C)增加，幅度大於28%
(D)减少，幅度小於14%
答案是:C
我的想法:令P1=200,000 P2=150,000 原本的需求量Q1 後来的需求量Q2
套入弧弹性的公式， ｜(Q2-Q1/Q2+Q1) 整个除以2｜
_____________________________ > 1
｜(P2-P1)/(P2+P1) 整个除以2｜
= = = = = = = = = = = = = = = = = = = = = = = = == ==
｜(Q2-Q1/Q2+Q1)｜ ｜(Q2-Q1/Q2+Q1)｜
____________________ = __________________ >1
｜-50,000/350,000｜ 1/7
= = = = = = = = = = = = = = = = = == === = = = = = = = = = = = = = =
｜(Q2-Q1/Q2+Q1)｜>7 所以 (Q2-Q1/Q2+Q1)>7 或 (Q2-Q1/Q2+Q1)<-7
= = = = = = = = = = = = = == = = = = = = = = = = = = = = = = = = = =
算出来Q2 >4/3 Q1 但怎麽会是大於28%呢？
高手可以帮我解惑吗？谢谢。
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1F：推 bot:变动百分比的分母是"(Q1+Q2)/2" 你算式算出来应该是1/7不是7 02/27 19:43
2F：→ bot:所以是 1/3.5 = 2/7 = 0.28 02/27 19:44
3F：推 bot:老师刚交到弹性、不知道这样对不对.... 02/27 19:46
4F：→ goshfju:把P变化的百分比求出来 , 需求量的变动会大於那个幅度 02/29 05:01
5F：推 askaaa:所以如果撇开计算不谈 其实一秒可以选答案.. 03/02 19:26