《GMAT加减法思维》连载10
来源: | 作者:passion | 发布时间: 2016-10-10 | 20147 次浏览 | 分享到:

第四节 去粗比精


“不看完选项我不知道答案。”

 

所以,去粗比精是针对选项来说的。去粗,要求去除绝对错误的选项,比精,要求选择相对更好的选项。

 

习惯了数学思维的考生,会在读完问题以后马上计算出答案,选项未看题目已经做完,剩下的不过是走个过场而已。这种思维是典型的学术思维,不考虑现实,追求理论上的完美方案。但是商科思维要求管理者在实际问题中就地取材,不求完美,只求最优。

 

我们举一个GMAT数学题的例子,说有一个长方形游泳池,长宽高分别为20米,10米,2米,问以下哪个选项最接近它的表面积。按照正常的计算步骤,我们可以轻松获得(20+10×2×2+20×10的公式,得到答案为320平方米,但是看完选项,同学们有点蒙。

 

A) 5万平米 B) 2平米 C) 800平米 D) 200平米 E) 18平米

 

难道我算错了?很多同学发出这样的疑问。反复读了几遍题,确认自己没算错只好找老师来问。

 

原因很简单:大家忽略了题目所问是“最接近”正确答案的那一个。按照GMAT减法思维的第四条,我们在看完选项之前不该妄自猜测答案长什么样子:“不看完选项不知道答案”。这个题就是如此,你得用320米作为标尺跟五个选项一一比较,谁离得最近谁就是答案,200平米跟320平米差120平米,却是五个里面最小的距离,因此答案就是D。在整个解题过程中,算出320只是走完了一半路程,真正的决战才刚拉开序幕而已。

 

作为管理者,需要的就是这样的思维过程。在确定方案前,根据已有的选项进行客观的比较与衡量,先否决不合底线要求的,再在合乎底线要求的选项里进行好坏的选择。这就是我们说的:先用定性原则去粗,再用定量标尺比精。

 

关于定性和定量的区别,我给各位形象的打个比方,就好比我们参加的高中考试,会考是定性的,不过就不能毕业,过了就可以参加高考;而高考是定量的,没有所谓过不过的说法,当题目特别难的时候,即便有几门不及格也保留着上名牌大学的希望。再比如说男人选择结婚伴侣,她再漂亮也不能是个疯子,她再丑也架不住我身边没别人了。因为漂亮不过是定量标尺,精神正常是不可违背的定性原则。因此在选择配偶的诸多标准中,定性原则是要打勾才能通过的,比如必须是女的,必须是异性恋者,必须三观接近。定量问题则本着“得之我幸、不得我命”的心态,比如相貌好坏,收入高低,身材胖瘦,等等。用这样的方式看待人生,往往可以迈过很多年轻时候迈不过的坎儿。

 

实际做题中,我们在去粗阶段定罪的选项,也会视乎不同的罪行,采用“秒杀”或“死缓”两种不同的处置方式。前者罪不可赦,根本无需二审,就地处决;后者则需要放在waitinglist里等等看,如果没有更好的选择也许摇身一变成了正宫娘娘。

 

以刚刚那道题为例,几十米见方的游泳池,无论如何表面积达不到5万,A选项直接死亡,再然后,闭着眼睛也知道表面积不会比边长更小,BE在枪声中作别。剩下CD,通过了底线标准的分界线,才需要动用比精的工具,也就是定量标尺进行精确衡量。

 

面对GMAT语文题时,这种在去粗和比精之间的切换就更加必不可少了。因为没有完美选项,我们不得不在各种残缺的选择中寻找毛病最小的那一个。不完美变成我们GMAT考生必须面对的现实!当然,不完美不意味着可以犯下致命的错误,死罪还是死缓的区分就在于评判标准属于定性原则,还是定量标尺。

 

SC题为例,我们经常在两个半斤八两的选项之间难以抉择,看这道题:

 

[1.8]

  • Over 75 percent of the energy produced in France derives from nuclear power, while in Germany it is just over 33 percent.

  • A) while in Germany it is just over 33 percent

  • B) compared to Germany, which uses just over 33 percent

  • C) whereas nuclear power accounts for just over 33 percent of the energy produced in Germany

  • D) whereas just over 33 percent of the energy comes from nuclear power in Germany

  • E) compared with the energy from nuclear power in Germany, where it is just over 33 percent

 

 

每个选项都有缺点,相比之下AC属于矬子里拔出的两个将军,A简洁但是不清晰(有歧义为:德国使用了来自法国生产的核能),C啰嗦但是更清晰。最终我们选择的是C,因为在SC中,歧义属于重罪,触犯了定性原则,啰嗦可以缓刑,二审时再用定量标尺比比。

 

再比如这道例题:

 

[1.9]

  • The Organization of Petroleum Exporting Countries (OPEC) had long been expected to announce a reduction in output to bolster sagging oil prices, but officials of the organization just recently announced that the group will pare daily production by 1.5 million barrels by the beginning of next year, but only if non-OPEC nations, including Norway, Mexico, and Russia, were to trim output by a total of 500,000 barrels a day. 

  • A year, but only if non-OPEC nations, including Norway, Mexico, and Russia, were to trim output

  • B year, but only if the output of non-OPEC nations, which includes Norway, Mexico, and Russia, is trimmed

  • C year only if the output of non-OPEC nations, including Norway, Mexico, and Russia, would be trimmed

  • D year only if non-OPEC nations, which includes Norway, Mexico, and Russia, were trimming output

  • E year only if non-OPEC nations, including Norway, Mexico, and Russia, trim output 


很多同学都对SC题目中的which vs.ing区别喜闻乐见,因为这种题规律性强,操作起来也比较容易上手。可是这道题目中的DE选项出现的which/ing问题,就没办法按照所谓“which就近”的方法来比较了。根据句意来说,include的动作发起者当然是就近的non-OPECnations,可是如果选择which,就犯了单复数不符的问题(nations是复数,includes是单数),在这个时候,which vs.ing就退位成了定量标尺,单复数才是定性原则。把握好这些不同测量标准之间的先后顺序,就构成了SC解题技巧的核心问题。

 

说完SC,我们还要说说CR。逻辑题中的不完美答案更加比比皆是。因为题目经常用moststrongly,或mostseriously来发出要求,比如下面这道:

 

[1.10]

In the year following an eight-centincrease in the federal tax on a pack of cigarettes, sales of cigarettes fellten percent. In contrast, in the year prior to the tax increase, sales hadfallen one percent. The volume of cigarette sales is therefore strongly relatedto the after-tax price of a pack of cigarettes.
Which of the following, if true, would most strengthen the argument above?

A During the second year after the tax increase, cigarette salesincreased by a significant amount. 

B The information available to consumers on the health risks of smokingremained largely unchanged in the period before and after the taxincrease.  

C Most consumers were unaware that the tax on cigarettes was going toincrease.

D During the year following the cigarette tax increase, many consumershad less income, in inflation-adjusted dollars, than they had had in theprevious year. 

E During the year after the tax increase, there was a greater varietyof cigarettes on the market than there had been during the previous year.

 

最终答案B,也就是税增长的前后一年人们对吸烟有害健康这件事了解程度没有改变,听上去好像跟原文一点关系没有,可答案偏偏就是听上去最不知所云的这一个。

 

SC题中,一个特别容易犯的错误思维,就是加强选项是建立结论的完整推理,削弱选项是推翻结论的推理过程。这种都是所谓的“百分百情结”,非要追求完美选项。

 

即使是RC,阅读,里面的选项比较也存在着绝对的排除,与相对的比较这两者的差异问题。也就是说,各位考生在面对选项时,要尽量优化比较的过程,按照风险大小来排序罪行的高低,进而选出错误概率最小,与问题要求最接近的那一个作为答案。


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