LSAT 109 | Section 1 | Logical Reasoning: Q23

LR Question 23 Explanation

QUESTION TEXT: An air traveler in Beijing cannot fly to Lhasa without first…

QUESTION TYPE: Parallel Reasoning

CONCLUSION: Any traveler flying from Beijing to Lhasa must fly through Xian.

REASONING: To get from Beijing to Lhasa one must pass through Chengdu. But to get from Beijing to Chengdu one must pass through Xian.

ANALYSIS: This is a good argument. Chengdu is a necessary condition for Beijing-Lhasa. And Xian is a necessary condition for Chengdu.

Beijing-Lhasa ➞ Chengdu ➞ Xian

___________

1. This is a bad argument. The patient could have felt drowsy instead of nervous.
2. CORRECT. Yellow ➞ Green ➞ White 
3. This is a bad argument. A powerful microscope is sufficient to allow us to examine a mushroom’s spores. But it isn’t necessary: there could be other ways to examine the spores. 
4. This is almost a good argument, but not quite. The conclusion ought to have said: there are two ways, therefore, for a person to fulfill a necessary condition for becoming fluent in a language. 
5. This is a bad argument. We can’t combine two “some” statements. It could be that the dancers who danced in both Sleeping Beauty and Swan Lake were not the same dancers who danced in both Giselle and Sleeping Beauty.