一道不知怎么解释的逻辑题, 请求大家帮忙

yidiyuehan

A recent report determined that although only 5 percent of homeowners in Stockton have outfitted their homes with burglar alarms, 25 percent of all Stockton homes that have been burglarized within the last five years were outfitted with them. Clearly, homeowners who outfit their homes with burglar alarms are more likely to become victims of burglary than are homeowners who do not.

The conclusion above depends on which of the following assumptions?  

A. The number of homes that were burglarized within the last five years is greater than the number of homes equipped with burglar alarms.
B. A significant number of the homes that were burglarized within the last five years were burglarized more than once within this time period.
C. Homes that have been burglarized within the last five years are more likely to be burglarized than are homes that have not been burglarized within the last five years.
D. Homeowners who outfit their homes with burglar alarms are less likely to become victims of burglary than are homeowners who have not installed such alarms.
E. Homeowners in Stockton who have outfitted their homes with burglar alarms are more likely to be victims of burglary than homeowners with burglar alarms living in other similar cities.

答案稍后公布.

francoiswang

C?

ethanrain824

期待答案 把自己给做迷茫了

我心向明月

我选C，这题和之前做过的一道题非常象：
http://forum.chasedream.com/GMAT_CR/thread-435210-1-1.html

yidiyuehan

是啊, 正确答案是C, 我看了解释还是很迷糊..............
有没有高人能够指点下? (最好不要用排除法)

francoiswang

文中通过过去五年被偷的情况来推一个笼统的结论，装alarm的比不装alarm的更容易被偷。中间有个GAP，所以答案一定要与过去五年的装alarm的家庭与不装alarm的家庭被偷的情况有关。就是在过去5年里，在所有被偷窃的家庭中，那25%装alarm的家庭更容易更多次数的被偷。
纯属菜鸟的个人意见~

flyingbunny

在所有homeowner 里面，只有5%的人装了burglar alarms（这里其实要假设每个 homeowner 只有1套房）；==>>只有5%的房子装了burglar alarms；
这个条件跟下面这个条件一起：
在所有被盗窃的房子里面， 25%装了burglar alarms ==>> 装了burglar alarms的房子跟容易被盗。

然后就推出 装 burglar alarms的homeowner更容易成为 victim.

flyingbunny

补充一下：
这题跟http://forum.chasedream.com/GMAT_CR/thread-435210-1-1.html
的共同点是给的前提的事实是一个，结论的事实是另一个。中间缺少的就是要把两个事实连起来的东西。

yidiyuehan

多谢楼上的回答, 无奈就是转不过这个弯............

感觉这中题目其实是一种类型, 所以还是要硬着头皮去攻克它...

前提:
5% 有警报
被偷盗的房子里, 25%是有警报的
结论:
==> 有警报的房子比没有警报的房子更容易被偷盗

假设:
过去五年被偷盗过的, 比没有被偷盗的房子 更容易被偷盗

实在是不明白这个假设是怎么出来的, 假设里面根本没有讲到警报啊.........

flyingbunny

多谢楼上的回答, 无奈就是转不过这个弯............

感觉这中题目其实是一种类型, 所以还是要硬着头皮去攻克它...

前提:
5% 有警报
被偷盗的房子里, 25%是有警报的
结论:
==> 有警报的房子比没有警报的房子更容易被偷盗

假设:
过去五年被偷盗过的, 比没有被偷盗的房子 更容易被偷盗

实在是不明白这个假设是怎么出来的, 假设里面根本没有讲到警报啊.........

-- by 会员 yidiyuehan (2010/1/27 10:57:54)

错了，不是“5% 有警报”， 是"5%的homeowner 装了警报"，这跟"5%的房子装了警报" 是完全不同的。