Manhattan 上一道与数学有关的逻辑题

jiaying52

做逻辑题的时候会出现不理解题目的情况，这题和数学相关，我觉得理解不了，求教大家；
10. Real Estate Prices
In the last year, real estate prices, such as those for houses and condominiums, have
gone up an average of 7% in the city of Galway but only 2% in the town ofTuam.
On the other hand, average rents for apartments have risen 8% in Tuam over the
last year, but only 4% in Galway.
Which of the following is an inference that can be reasonably drawn from the prem-
ises given above?
(A) In the last year, the ratio of average apartment rents to average real estate prices
has increased in Tuam but fallen in Galway.
(B) Tuam has experienced a greater shift in demand toward the rental market than
Galway has.
(C) It has become easier for Galway real estate to be bought and sold, whereas it has
become easier for Tuam real estate to be rented.
(D)The supply of rental apartment units has decreased more in Tuam than in
Galway.
(E) The average amount spent on housing is higher in Galway than it is in Tuam.
The question presents two trends in the real estate market in each of two cities and asks for an inference that can be drawn from these facts.
答案选A Manhattan给出的解释如下：

A) CORRECT. In Tuam, rents have gone up at a faster rate (8%) than real estate prices (2%).
Thus, the ratio of average rents to average real estate prices must have grown in that city-the numerator has grown faster than the denominator. In contrast, Galway rents have gone up atslower rate (4%) than real estate prices (7%). Thus, the ratio of average rents to average real estate prices has actually decreased.
看不懂解释中为什么说分子比分母增加的多就是increase. 而分母比分子增加的多就是drecrease

dengts

分子越大，分数越大，分母越大，分数越小

jiaying52

估计我没讲清楚，我想问的是原文和解释中说的单位名词是百分比-以租房价为例：【（现在租房价-原租房价）/原房价-1】*100%
答案A里面说的是租房价
两个单位不一样的 应该是不同的变量
所以我不明白是怎么从原文推导出A选项的

jiaying52

分子越大，分数越大，分母越大，分数越小

-- by 会员 dengts (2011/4/10 19:15:04)

谢谢，不过貌似我的表达不清楚！

dengts

分子越大，分数越大，分母越大，分数越小

-- by 会员 dengts (2011/4/10 19:15:04)

谢谢，不过貌似我的表达不清楚！

-- by 会员 jiaying52 (2011/4/10 20:58:53)

A也是比啊

dengts

the ratio of average apartment rents to average real estate prices
就是租金比价格啊

jiaying52

the ratio of average apartment rents to average real estate prices
就是租金比价格啊

-- by 会员 dengts (2011/4/10 21:35:46)

the ratio of average apartment rents to average real estate prices= 平均租金：平均房价（两个都是定量）
而原文中说的是average apartment rent increase的percentage =｛（现在的平均租金-过去的平均租金）/过去的租金-1】*100%
average real estate prices给的百分比=【（现在平均房价-过去平均房价)/过去的平均房价-1】*100%

两者的概念应该是不一样的吧 如果要建立关系应该有个推导过程吧？

dengts

the ratio of average apartment rents to average real estate prices
就是租金比价格啊

-- by 会员 dengts (2011/4/10 21:35:46)

the ratio of average apartment rents to average real estate prices= 平均租金：平均房价（两个都是定量）
而原文中说的是average apartment rent increase的percentage =｛（现在的平均租金-过去的平均租金）/过去的租金-1】*100%
average real estate prices给的百分比=【（现在平均房价-过去平均房价)/过去的平均房价-1】*100%

两者的概念应该是不一样的吧 如果要建立关系应该有个推导过程吧？

-- by 会员 jiaying52 (2011/4/10 21:57:08)

A说了比率上升了啊。。。。平均租金=过去租金（现在的平均租金-过去的平均租金）/过去的租金+1），平均房价=过去房价（现在平均房价-过去平均房价)/过去的平均房价+1）