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标题: 一道弄晕我的因果关系问题--LSAT-1-4-21 [打印本页]
作者: gracehu 时间: 2003-11-29 10:17
标题: 一道弄晕我的因果关系问题--LSAT-TEST1-SEC IV
21. A low-pressure weather system is approaching Plainville; rainfall results from about 70 percent of such systems in the Plainville area. Moreover, the current season, spring, is the time of year in which thundershowers, which sometimes result from low-pressure systems, are most likely to occur in Plainville.
Knowing which one of the following, in addition to the information above, would be most useful for determining the probability that Plainville will have a thundershower soon?
(A) the percentage of thundershowers in Plainville that occur in the spring
(B) the percentage of spring rainfalls in Plainville that are thundershowers
(C) the percentage of thundershowers in Plainville that result from low-pressure systems
(D) whether low-pressure systems in other areas are associated with rainfall
(E) whether Plainville has more or fewer thundershowers each spring than do nearby towns
The answer is B! Why not C?
Thx in advance for any explanation
[此贴子已经被作者于2003-11-29 10:23:29编辑过]
作者: gracehu 时间: 2003-11-29 10:25
会不会是因为问题中的'IN ADDITION TO'啊?
作者: browse 时间: 2003-11-29 11:09
注意C并不能推出spring 的 thundershower probability, 它可能是全年的结果。
而由B我们可以从lowpressure * 70%--->rainfall possibility + B中条件(spring rainfalls that are thundershowers)----> the possibility of spring thundershower rainfalls under lowpressure weather system.
以下是引用gracehu在2003-11-29 10:17:00的发言：21. A low-pressure weather system is approaching Plainville; rainfall results from about 70 percent of such systems in the Plainville area. Moreover, the current season, spring, is the time of year in which thundershowers, which sometimes result from low-pressure systems, are most likely to occur in Plainville.
Knowing which one of the following, in addition to the information above, would be most useful for determining the probability that Plainville will have a thundershower soon?
(A) the percentage of thundershowers in Plainville that occur in the spring
(B) the percentage of spring rainfalls in Plainville that are thundershowers
(C) the percentage of thundershowers in Plainville that result from low-pressure systems
(D) whether low-pressure systems in other areas are associated with rainfall
(E) whether Plainville has more or fewer thundershowers each spring than do nearby towns
The answer is B! Why not C?
Thx in advance for any explanation
[此贴子已经被作者于2003-11-29 10:23:29编辑过]
作者: Snazzy 时间: 2003-11-29 11:52
标题: THUNDERSHOWER, OH, COME ON ...
Hi, there, i have got the right answer and am trying to give you an explanation, which you might agree with:
Since both rainfall and thundershower result from low-pressure weather system, it's enough to only consider the possibility of thundershower(thunder with rainfall). We already know there is 70 percent of the chance to have rainfall. If we know the percentage of thunder with rainfall, say 40%, it is easy to know the possibility of thurdershower, which is 70% times 40%, 28%. (0-grade Math PS) Snazzy Nov. 28
21. a low-pressure weather system is approaching plainville; rainfall results from about 70 percent of such systems in the plainville area. moreover, the current season, spring, is the time of year in which thundershowers, which sometimes result from low-pressure systems, are most likely to occur in plainville.
knowing which one of the following, in addition to the information above, would be most useful for determining the probability that plainville will have a thundershower soon?
(a) the percentage of thundershowers in plainville that occur in the spring
(b) the percentage of spring rainfalls in plainville that are thundershowers
(c) the percentage of thundershowers in plainville that result from low-pressure systems
(d) whether low-pressure systems in other areas are associated with rainfall
(e) whether plainville has more or fewer thundershowers each spring than do nearby towns
the answer is b! why not c?
thx in advance for any explanation
作者: mariezhu 时间: 2003-11-29 17:36
这道题讨论过，搜索一下吧！
另外文中已经有thundershower和lowpressure weather system的关系了，
缺的是rainfall和thundershower的关系
作者: gracehu 时间: 2003-11-30 06:32
标题: 一道弄晕我的因果关系问题--LSAT-1-4-21
thx!browse,Snazzy,mareizhu! The explanations are very clear and helpful!
作者: dphxmg 时间: 2005-3-26 22:28
C所要表达的是由low-pressure system 所导致的thundershowers 占到所有thundershowers 的多少。因此，你不可能知道仅由这个比率来预测未来的某个low-pressure system有多大可能带来thundershowers.
the percentage of thundershowers in Plainville that result from low-pressure systems
如果C 被改成the percentage of low-pressure systems in Plainville that result in thundershowers, 那末，它就能成为一个好的选项。
作者: jameswoods 时间: 2005-4-21 11:10
以下是引用dphxmg在2005-3-26 22:28:00的发言：C所要表达的是由low-pressure system 所导致的thundershowers 占到所有thundershowers 的多少。因此，你不可能知道仅由这个比率来预测未来的某个low-pressure system有多大可能带来thundershowers.
the percentage of thundershowers in Plainville that result from low-pressure systems
如果C 被改成the percentage of low-pressure systems in Plainville that result in thundershowers, 那末，它就能成为一个好的选项。
dphxmg GG 的回复令人豁然开朗，
顶
作者: beautyup 时间: 2005-6-7 20:57
同意七楼的解释！
C)选项的表述有问题！
作者: quiny 时间: 2005-7-30 22:17
3x
作者: amywangwei 时间: 2008-6-1 20:34
同意7楼和3楼，醍醐灌顶！
作者: raoshe 时间: 2008-6-2 11:45
凑个热闹，我的解法如下，不当之处恳请批评指正，以促进步。
该题逻辑线索为:
第一句话：low-pressure systerm→rainfall
第二句话：low-pressure systerm→thundershowers
根据三段论的第三格：Ｍ－Ｐ
Ｍ－Ｓ
——————
Ｓ－Ｐ
可知，要使作者论证成立则必有：thundershowers－rainfall
答案为Ｂ。Ｃ和Ｄ按照公共元素不在正确答案出现的规则，不必待逻辑线索列出，就可以首先排除了。
作者: cocuchi 时间: 2008-6-15 17:24
7楼太牛了
作者: taoransk 时间: 2010-10-1 17:46
刚看到这个问题.....虽然已经很早了. 但是我想问问我的情况是否正确...
厄, 我是这么推的
1. low-pressure --> local area
2. low-presssure --> rainfall (70%) --> at Local area
3. low-pressure --> thundershowers --> at Local area & at resent time period (spiring, now)
第一句提出背景
第二句由背景延伸出一个结果,及地点限定
第三句由背景延伸出另一个结果,及地点限定,并且附加时间限定
问题是要将另一个结果(雷雨)推算出百分比.只有前一个结果提出百分比问题,所以必须与前一结果(下雨)结合,
A是将雷雨和时间限定结合
B是将雷雨和下雨(有百分比)结合
C是将雷雨和背景(低压)结合
D是将雷雨和其他地区..这个完全out of scope
E是与过往时间限定对比,也是out fo scope
所以我没看出BC 有什么相似啊, 在说两个东西呢, 除了下雨和雷雨, 其他任何条件(背景,时间限定, 地点限定) 都无法在提供单独一个比例的情况下推算雷雨比例, 因为只有下雨几率是有翔实比例数据的
另, 后来看了下回复, 7楼貌似有点问题, 11楼和我一样推的,呵呵
作者: newstart1322 时间: 2013-12-8 13:42
mariezhu 发表于 2003-11-29 17:36 
这道题讨论过，搜索一下吧！另外文中已经有thundershower和lowpressure weather system的关系了，缺的是rai ...
嗯，懂了！
作者: Bensontuo 时间: 2019-7-23 20:00
1. Correlation never proves causality
2. 2 things happened coincidentally with one and another does not prove any causality either.
3. When A happen, B, and C also happened, it does not mean A is the cause for both B&C, it could be A is " coincidentally happened when B cause C or C cause B.
Core question: The determining factor of the probability that plainville will have a thundershower soon.
Well... Thundershower means thunder and rainfalls, so all we have to do is to calculate the possibilities of exactly when thunder happens, rainfalls also happens at spring seasons.
So let us say that spring seasons are 4 months as total, which are 120 days, and within those 120 days, we have exactly 84 days ( 120 * 0.7 ) are days with rainfalls, and if we do have a exact numbers and dates of thunder happened within those 120 days, we can know within that 84 days of rainfall, when do we have the day with not only rainfalls but also thunders. lets make up a number as 20 days, both rain and thunder.
In that sense, the percentage of spring rainfalls in Plainville that are thundershower could be calculated as 20/84.
C. Please please please ensure that you are not going to be distracted by " low pressure systems ". If you are figuring the percentage of thundershowers due to low pressure system, then you can only have use that outcome to versus the percentage of thundershowers " not due to " low pressure system. However, even we do have the exact answer from that versus relationship, we still can't determine the probability of the thundershower at plainville.
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