一些逻辑问题的分析

aomeisoft7

想问一下LZ 关于ONLY if 和 if ONLY 的区别的

比如说： A ONLY if B。应该是说 A能推出B， B是A 的必要条件对吧？

after A， B 是B能推出A的意思么？

那A if ONLY B 是啥意思？

-- by 会员 橘子骨头 (2010/10/5 19:56:51)

A only if B    A能推出B，B是A的必要条件。 要使A成立，必须B成立。
                    比如 ： 苹果 only if 水果， 要是苹果，必须得先是水果
A if only B    B能推出A，B是A的充分条件。只要B成立，A就成立。
                    比如：水果 if only 苹果 ，只要是苹果，就一定是水果
after A, B  是B能推出A

keith139

86.    (24835-!-item-!-188;#058&001244)

Which of the following most logically completes the passage?
Concerned about the financial well-being of its elderly citizens, the government of Runagia decided two years ago to increase by 20 percent the government-provided pension paid to all Runagians over 65.  Inflation in the intervening period has been negligible, and the increase has been duly received by all eligible Runagians.  Nevertheless, many of them are no better off financially than they were before the increase, in large part because __________.
A. they rely entirely on the government pension for their income
B. Runagian banks are so inefficient that it can take up to three weeks to cash a pension check
C. they buy goods whose prices tend to rise especially fast in times of inflation
D. the pension was increased when the number of elderly Runagians below the poverty level reached an all-time high
E. in Runagia children typically supplement the income of elderly parents, but only by enough to provide them with a comfortable living
这道我觉得应该选C，为什么答案是E呢？孩子给老人的钱，和政府的补助有什么关联？孩子给老人的钱只能提供个温饱，加上政府给的，那不就应该更好了么。为何是E啊？

-- by 会员 Helloface (2010/9/24 15:54:20)

这和上面那一题思路是一样的
E. in Runagia children typically supplement the income of elderly parents, but only by enough to provide them with a comfortable living
孩子给的钱，只使 老人 能维持在温饱水平。比如温饱要500，政府补贴400，孩子就给100
现在政府多出100，政府补贴了500，老人到温饱了，孩子就不补助了

-- by 会员 aomeisoft7 (2010/9/24 17:07:56)

这个题基本上跟OG12中的22题一模一样，关于e选项，我有这样的问题：如果welfare本身在20%增长前就够老人生活的很好，那么增长之后不就应该更好了么？？楼主说的状况中有个假设是增长前后政府的welfare都不够基本生活，或者生活的comfortable。然而这个假设并没有提示说存在啊。
22的答案是c

aomeisoft7

86.    (24835-!-item-!-188;#058&001244)

Which of the following most logically completes the passage?
Concerned about the financial well-being of its elderly citizens, the government of Runagia decided two years ago to increase by 20 percent the government-provided pension paid to all Runagians over 65.  Inflation in the intervening period has been negligible, and the increase has been duly received by all eligible Runagians.  Nevertheless, many of them are no better off financially than they were before the increase, in large part because __________.
A. they rely entirely on the government pension for their income
B. Runagian banks are so inefficient that it can take up to three weeks to cash a pension check
C. they buy goods whose prices tend to rise especially fast in times of inflation
D. the pension was increased when the number of elderly Runagians below the poverty level reached an all-time high
E. in Runagia children typically supplement the income of elderly parents, but only by enough to provide them with a comfortable living
这道我觉得应该选C，为什么答案是E呢？孩子给老人的钱，和政府的补助有什么关联？孩子给老人的钱只能提供个温饱，加上政府给的，那不就应该更好了么。为何是E啊？

-- by 会员 Helloface (2010/9/24 15:54:20)

这和上面那一题思路是一样的
E. in Runagia children typically supplement the income of elderly parents, but only by enough to provide them with a comfortable living
孩子给的钱，只使 老人 能维持在温饱水平。比如温饱要500，政府补贴400，孩子就给100
现在政府多出100，政府补贴了500，老人到温饱了，孩子就不补助了

-- by 会员 aomeisoft7 (2010/9/24 17:07:56)

这个题基本上跟OG12中的22题一模一样，关于e选项，我有这样的问题：如果welfare本身在20%增长前就够老人生活的很好，那么增长之后不就应该更好了么？？楼主说的状况中有个假设是增长前后政府的welfare都不够基本生活，或者生活的comfortable。然而这个假设并没有提示说存在啊。
22的答案是c

-- by 会员 keith139 (2010/10/5 22:14:29)

这2题不是一模一样的
PREP的这道题E选项不是假设，是支持。
政府要提高补助，原因就是老人的生活不好，就像社会低保，如果老人之前的生活就很好了，政府就没有必要增加补助了。（当然这只是常识推理，题目并没有说）


这题和OG的主要区别是 对inflation的定义
这题说 Inflation in the intervening period has been negligible
已经明确说忽略inflation，所以再考虑inflation的影响就不对了。
即使考虑通胀，inflation很小很小，prices tend to rise especially fast in times of inflation，价格增长比inflation快再多，还是很小的。
这和OG一道阅读题很像,OG12,阅读117题对D选项的解释，可以看下


OG这道题对inflation的定义是
the annual rate of inflation since the pension increase has been below 5 percent.
说明这题考虑到了inflation的影响

keith139

86.    (24835-!-item-!-188;#058&001244)

Which of the following most logically completes the passage?
Concerned about the financial well-being of its elderly citizens, the government of Runagia decided two years ago to increase by 20 percent the government-provided pension paid to all Runagians over 65.  Inflation in the intervening period has been negligible, and the increase has been duly received by all eligible Runagians.  Nevertheless, many of them are no better off financially than they were before the increase, in large part because __________.
A. they rely entirely on the government pension for their income
B. Runagian banks are so inefficient that it can take up to three weeks to cash a pension check
C. they buy goods whose prices tend to rise especially fast in times of inflation
D. the pension was increased when the number of elderly Runagians below the poverty level reached an all-time high
E. in Runagia children typically supplement the income of elderly parents, but only by enough to provide them with a comfortable living
这道我觉得应该选C，为什么答案是E呢？孩子给老人的钱，和政府的补助有什么关联？孩子给老人的钱只能提供个温饱，加上政府给的，那不就应该更好了么。为何是E啊？

-- by 会员 Helloface (2010/9/24 15:54:20)

这和上面那一题思路是一样的
E. in Runagia children typically supplement the income of elderly parents, but only by enough to provide them with a comfortable living
孩子给的钱，只使 老人 能维持在温饱水平。比如温饱要500，政府补贴400，孩子就给100
现在政府多出100，政府补贴了500，老人到温饱了，孩子就不补助了

-- by 会员 aomeisoft7 (2010/9/24 17:07:56)

这个题基本上跟OG12中的22题一模一样，关于e选项，我有这样的问题：如果welfare本身在20%增长前就够老人生活的很好，那么增长之后不就应该更好了么？？楼主说的状况中有个假设是增长前后政府的welfare都不够基本生活，或者生活的comfortable。然而这个假设并没有提示说存在啊。
22的答案是c

-- by 会员 keith139 (2010/10/5 22:14:29)

这2题不是一模一样的
PREP的这道题E选项不是假设，是支持。
政府要提高补助，原因就是老人的生活不好，就像社会低保，如果老人之前的生活就很好了，政府就没有必要增加补助了。（当然这只是常识推理，题目并没有说）


这题和OG的主要区别是 对inflation的定义
这题说 Inflation in the intervening period has been negligible
已经明确说忽略inflation，所以再考虑inflation的影响就不对了。
即使考虑通胀，inflation很小很小，prices tend to rise especially fast in times of inflation，价格增长比inflation快再多，还是很小的。
这和OG一道阅读题很像,OG12,阅读117题对D选项的解释，可以看下


OG这道题对inflation的定义是
the annual rate of inflation since the pension increase has been below 5 percent.
说明这题考虑到了inflation的影响

-- by 会员 aomeisoft7 (2010/10/5 23:11:12)

哦~~~~
谢谢楼主！
5%在OG里必定被认为是会有影响的部分了，也就是增加的20%的养老金不足以抵消那些特殊商品的>5%的inflation影响。不可以视作negligible的啦，所以这个OG题关键是对inflation的average和大于平均值的考点。而这个题是另外一个原因。这两个题对比着看效果很好的说！至少有两种可能来解释这个discrepancy，如果考虑通胀的话。开拓了思路……
再次感谢

keith139

Researchers took a group of teenagers who had never smoked and for one year tracked whether they took up smoking and how their mental health changed. Those who began smoking within a month of the study’s start were four times as likely to be depressed at the study’s end than those who did not begin smoking. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers.

Which of the following, if true, most strengthens the argument?

A.    articipants who were depressed at the study’s start were no more likely to be smokers at the study’s end than those who were not depressed.
B.    articipants who began smoking within a month of the study’s start were no more likely than those who began midway through to have quit smoking by the study’s end.
C.    Few, if any, of the participants in the study were friends or relatives of other participants.
D.    Some participants entered and emerged from a period of depression within the year of the study.
E.    The researchers did not track use of alcohol by the teenagers.
答案是A，求解~~~

-- by 会员 Helloface (2010/9/30 17:13:12)

研究发现：抽烟的人depressed的概率是 不抽烟的人 的4倍。结论：尼古丁改变大脑chemistry，因此改变mood，所以抽烟是他们depression的原因


求支持


A.    articipants who were depressed at the study’s start were no more likely to be smokers at the study’s end than those who were not depressed.
抽烟的人 比 不抽烟的人 在研究结束时 更不愿再成为抽烟者了。因为他们发现抽烟使他们depressed,所以他们不愿意再吸烟了，支持了是抽烟造成depression的原因
B.    articipants who began smoking within a month of the study’s start were no more likely than those who began midway through to have quit smoking by the study’s end.
抽了1个月的 没有比 抽了半个月 的人 更想quit smoking。即smoking没有给他们造成影响，削弱结论
C.    Few, if any, of the participants in the study were friends or relatives of other participants.
很少的研究参与者是朋友。无关
D.    Some participants entered and emerged from a period of depression within the year of the study.
some的样本直接排除
E.    The researchers did not track use of alcohol by the teenagers.
和alcohol无关

-- by 会员 aomeisoft7 (2010/9/30 18:21:49)

LZ是逻辑达人啊，我这两天在看这个帖子，受益匪浅啊~
我的个人看法啊，关于这个题目，A选项是说在start的时候，那些本来就depressed的人到了end的时候不会比那些到了实验end时始终没抽烟的人更容易抽烟。就是排除了depress造成抽烟的因果倒置的情况。

Brooksxue

（问一道关于逻辑费费的题，一开始就卡住了， 请问有没有逻辑费费的讨论帖 发一个链接给我吧）
1. Although 90 percent of the population believes itself to be well informed about health care, only 20 percent knows enough about DNA. So apparently at least 80 percent of the population does not know enough about medical concepts to make well-informed personal medical choices or to make good public policy decisions about health care.

The argument’s reasoning is questionable because the argument fails to demonstrate that

A.    those people who can understand news stories about DNA are able to make well-informed personal medical choices
B.    more than 20 percent of the population needs to be well informed about health care for good public policy decisions about health care to be made
C.    one’s being able to make well-informed personal medical choices ensures that one makes good public policy decisions about health care
D.    an understanding of DNA is essential to making well-informed personal medical choices or to making good public policy decisions about health care
E.    since 90 percent of the population believes itself to be well informed about health care, at least 70 percent of the population is mistaken in that belief.

答案：D
请问A和D有什么不同

aomeisoft7

Researchers took a group of teenagers who had never smoked and for one year tracked whether they took up smoking and how their mental health changed. Those who began smoking within a month of the study’s start were four times as likely to be depressed at the study’s end than those who did not begin smoking. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers.

Which of the following, if true, most strengthens the argument?

A.    articipants who were depressed at the study’s start were no more likely to be smokers at the study’s end than those who were not depressed.
B.    articipants who began smoking within a month of the study’s start were no more likely than those who began midway through to have quit smoking by the study’s end.
C.    Few, if any, of the participants in the study were friends or relatives of other participants.
D.    Some participants entered and emerged from a period of depression within the year of the study.
E.    The researchers did not track use of alcohol by the teenagers.
答案是A，求解~~~

-- by 会员 Helloface (2010/9/30 17:13:12)

研究发现：抽烟的人depressed的概率是 不抽烟的人 的4倍。结论：尼古丁改变大脑chemistry，因此改变mood，所以抽烟是他们depression的原因


求支持


A.    articipants who were depressed at the study’s start were no more likely to be smokers at the study’s end than those who were not depressed.
抽烟的人 比 不抽烟的人 在研究结束时 更不愿再成为抽烟者了。因为他们发现抽烟使他们depressed,所以他们不愿意再吸烟了，支持了是抽烟造成depression的原因
B.    articipants who began smoking within a month of the study’s start were no more likely than those who began midway through to have quit smoking by the study’s end.
抽了1个月的 没有比 抽了半个月 的人 更想quit smoking。即smoking没有给他们造成影响，削弱结论
C.    Few, if any, of the participants in the study were friends or relatives of other participants.
很少的研究参与者是朋友。无关
D.    Some participants entered and emerged from a period of depression within the year of the study.
some的样本直接排除
E.    The researchers did not track use of alcohol by the teenagers.
和alcohol无关

-- by 会员 aomeisoft7 (2010/9/30 18:21:49)

LZ是逻辑达人啊，我这两天在看这个帖子，受益匪浅啊~
我的个人看法啊，关于这个题目，A选项是说在start的时候，那些本来就depressed的人到了end的时候不会比那些到了实验end时始终没抽烟的人更容易抽烟。就是排除了depress造成抽烟的因果倒置的情况。

-- by 会员 keith139 (2010/10/6 12:07:47)

这题我对A的理解是有误...
这句话太绕了，我要再研究下...

hjxsparrow

（问一道关于逻辑费费的题，一开始就卡住了， 请问有没有逻辑费费的讨论帖 发一个链接给我吧）
1. Although 90 percent of the population believes itself to be well informed about health care, only 20 percent knows enough about DNA. So apparently at least 80 percent of the population does not know enough about medical concepts to make well-informed personal medical choices or to make good public policy decisions about health care.

The argument’s reasoning is questionable because the argument fails to demonstrate that

A.    those people who can understand news stories about DNA are able to make well-informed personal medical choices
B.    more than 20 percent of the population needs to be well informed about health care for good public policy decisions about health care to be made
C.    one’s being able to make well-informed personal medical choices ensures that one makes good public policy decisions about health care
D.    an understanding of DNA is essential to making well-informed personal medical choices or to making good public policy decisions about health care
E.    since 90 percent of the population believes itself to be well informed about health care, at least 70 percent of the population is mistaken in that belief.

答案：D
请问A和D有什么不同

-- by 会员 Brooksxue (2010/10/6 21:13:48)

A.    those people who can understand news stories about DNA are able to make well-informed personal medical choices
懂DNA的 可以 make well-informed personal medical choices
没有说只有懂DNA的菜可以make well-informed personal medical choices

D.    an understanding of DNA is essential to making well-informed personal medical choices or to making good public policy decisions about health care
重点在is essential to
懂DNA是make well-informed personal medical choices的基础
只有懂DNA才能make well-informed personal medical choices
而懂DNA的只有20%，因此才能说明make well-informed personal medical choices的只会少于20%

aomeisoft7

（问一道关于逻辑费费的题，一开始就卡住了， 请问有没有逻辑费费的讨论帖 发一个链接给我吧）
1. Although 90 percent of the population believes itself to be well informed about health care, only 20 percent knows enough about DNA. So apparently at least 80 percent of the population does not know enough about medical concepts to make well-informed personal medical choices or to make good public policy decisions about health care.

The argument’s reasoning is questionable because the argument fails to demonstrate that

A.    those people who can understand news stories about DNA are able to make well-informed personal medical choices
B.    more than 20 percent of the population needs to be well informed about health care for good public policy decisions about health care to be made
C.    one’s being able to make well-informed personal medical choices ensures that one makes good public policy decisions about health care
D.    an understanding of DNA is essential to making well-informed personal medical choices or to making good public policy decisions about health care
E.    since 90 percent of the population believes itself to be well informed about health care, at least 70 percent of the population is mistaken in that belief.

答案：D
请问A和D有什么不同

-- by 会员 Brooksxue (2010/10/6 21:13:48)

90%的人相信他们很了解健康知识。但只有20%了解DNA。结论：很明显至少80%的人没有足够医学概念去做医疗选择和做好的社会医疗政策决定
求假设
A.    those people who can understand news stories about DNA are able to make well-informed personal medical choices
知道DNA的人知道怎么医疗选择。new stories这个概念是题干里没有的，而且这个选项也缺少了making good public policy decisions about health care。这就是和D的区别
D.    an understanding of DNA is essential to making well-informed personal medical choices or to making good public policy decisions about health care
DNA是做好医疗选择和好政策的关键因素

Brooksxue

谢谢各位大侠啊