prep逻辑一道，百思不得其解，请NN点拨

bbltxl · 发表于 2011-3-31 15:20:14

ps:谁知道怎么在帖子里贴图的也顺便教教我哈。。。

题目是这样的：
In a certain wildlife park, park rangers are able to track the movements of many rhinoceroses because those animals wear radio collars. When, as often happens, a collar slips off, it is put back on. Putting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilizer dart. Female rhinoceroses that have been frequently recollared have significantly lower fertility rates than uncollared females. Probably, therefore, some substance in the tranquilizer inhibits fertility.
In evaluating the argument, it would be most useful to determine which of the following?
a. Whether there are more collared female rhinoceroses than uncollared female rhinoceroses in the park
b. How the tranquilizer that is used for immobilizing rhinoceroses differs, if at all, from tranquilizers used in working with other large mammals
c. How often park rangers need to use tranquilizer darts to immobilize rhinoceroses for reasons other than attaching radio collars
d. Whether male rhinoceroses in the wildlife park lose their collars any more often than the park's female rhinoceroses do
e. Whether radio collars are the only practical means that par rangers have for tracking the movements of thinoceroses in the park.

答案是C，完全没懂，觉得都是无关。。。。
大家帮帮忙啦

littlexian · 发表于 2011-3-31 15:49:01

Answer C. The key point is that "Female rhinoceroses that have been frequently recollared (shot by tranquilizer) have significantly lower fertility rates than uncollared females. Probably, therefore, some substance in the tranquilizer inhibits fertility." If it is true, we have to make sure that those "uncollared females" did not get shot by tranquilizer as often as "frequently recollared females". Otherwise, if both frequently recollared and uncollared females got shot by tranquilizer equally, we wont be able to say that the lower fertility issue is because the tranquilizer shots.

bbltxl · 发表于 2011-3-31 15:54:16

太感谢啦！解释的很清楚

sdcar2010 · 发表于 2011-3-31 21:40:51

The premises: 1) Tranquilizer used during recollarization: Recollared --> tranquilizer used
2) Recollared females have low fertility. Recollared --> low fertility
The conclusion: some substance in the tranquilizer inhibits fertility: tranquilizer used --> low fertility

For this argument to hold, the assumption is that NOTHING other than the tranquilizer can cause low fertility.

C is the answer since
1) If further evidence shows that never-recollared females who have been tranquilized also have low fertility, then the argument is strengthened.

2) If futher evidence shows that never-recollared females who have been tranquilized do NOT have low fertility, then the argument is weakened.

C) How often park rangers need to use tranquilizer darts to immobilize rhinoceroses for reasons other than attaching radio collars?

If we know that the tranquilizer is never used other than collarizing rhinos, the argument is valid.

However, if we know that the tranquilizer is used in other situations on female rhinos, plus the info from the stimulus that these affected female rhinos do not have low fertility rate, then the argument that the tranquilizer causes low fertility in female rhinos will be in trouble.

Therefore, whether tranquilizer is used in other situations is an important information to have for the evaluation of the argument.

As to the strengthening or weakening aspect, you have to look at the conclusion, which links the tranquilizer to low fertility. If new findings add more weight behind the conclusion, it's a strengthener. If new finidings cast doubt on the conclusion, it's a weakener.

lpbird · 发表于 2011-11-7 14:27:10

How to explain tranquilizer is used in other situations on female rhinos that are collared as well. 这个选项只是比较了不同原因下的镇静剂使用频率，跟戴没戴项圈没关吧。

本贴相关题目 GMATPrep-2008E2-CR-74 (CXHU)

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