LSAT 135 – Section 4 – Question 09

LSAT 135 - Section 4 - Question 09

December 2011

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT135 S4 Q09
+LR
Most strongly supported +MSS
Conditional Reasoning +CondR
A
4%
158
B
8%
160
C
2%
156
D
2%
157
E
85%
165
130
143
155
 +Medium 147.853 +SubsectionMedium

Birds and mammals can be infected with West Nile virus only through mosquito bites. Mosquitoes, in turn, become infected with the virus when they bite certain infected birds or mammals. The virus was originally detected in northern Africa and spread to North America in the 1990s. Humans sometimes catch West Nile virus, but the virus never becomes abundant enough in human blood to infect a mosquito.

Summary
Birds and mammals are infected with West Nile virus only through bites from mosquitoes. Mosquitos become infected when they bite infected birds or mammals. The virus was first detected in Africa and spread to North America. Humans can catch West Nile virus, but infected humans cannot infect a mosquito.

Strongly Supported Conclusions
Mosquitos infected with West Nile virus have been present in Africa and North America.
Humans are sometimes bitten by mosquitos infected with West Nile virus.

A
West Nile virus will never be a common disease among humans.
Unsupported. Humans can get the virus from mosquitoes, so they may be bitten by infected mosquitoes in large numbers in the future. There’s no evidence this won’t happen.
B
West Nile virus is most common in those parts of North America with the highest density of mosquitoes.
Unsupported. We know that humans can get West Nile virus, but we don’t know how common the virus is among mosquito populations in North America. Perhaps it’s most common in specific parts without dense mosquito populations.
C
Some people who become infected with West Nile virus never show symptoms of illness.
Unsupported. We don’t know anything about the symptoms of West Nile virus and whether people can have the virus without exhibiting symptoms.
D
West Nile virus infects more people in northern Africa than it does in North America.
Unsupported. We know that the virus was first detected in northern Africa. We don’t know whether that suggests the virus infects more people there than in North America. Maybe there are far fewer people to be infected there? Maybe the virus is more common North America?
E
West Nile virus was not carried to North America via an infected person.
Strongly supported. We know that infected humans cannot infect a mosquito. So, if the virus was found in North America, that means a mosquito must have bitten an infected bird or mammal. Either that mosquito or the infected bird or mammal carried the virus to North America.

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LSAT PrepTest 135 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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