LSAT 139 – Section 1 – Question 15

LSAT 139 - Section 1 - Question 15

June 2013

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT139 S1 Q15
+LR
Resolve reconcile or explain +RRE
Causal Reasoning +CausR
Net Effect +NetEff
A
4%
157
B
6%
156
C
87%
165
D
1%
153
E
1%
157
140
148
156
 +Medium 142.273 +SubsectionEasier

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To reduce the mosquito population in a resort area, hundreds of trees were planted that bear fruit attractive to birds. Over the years, as the trees matured, they attracted a variety of bird species and greatly increased the summer bird population in the area. As expected, the birds ate many mosquitoes. However, the planting of the fruit trees had the very opposite of its intended effect.

"Surprising" Phenomenon
Why did planting trees that attracted birds end up increasing the mosquito population, even though the trees did attract birds and the birds did eat many mosquitoes?

Objective
The correct answer should describe an effect of the trees or of the birds attracted to the area that could result in an increase in mosquitoes.

A
Most of the species of birds that were attracted by the trees that were planted did not eat mosquitoes.
The stimulus tells us “the birds at many mosquitoes.” Even if most of the bird species didn’t eat mosquitoes, we still know many mosquitoes were eaten by birds. So, we’d still expect the mosquito population to go down.
B
The species of birds that were attracted in the greatest number by the fruit of the trees that were planted did not eat mosquitoes.
The stimulus tells us “the birds at many mosquitoes.” Even if the species that had the most birds didn’t eat mosquitoes, we still know many mosquitoes were eaten by birds. So, we’d still expect the mosquito population to go down.
C
The birds attracted to the area by the trees ate many more insects that prey on mosquitoes than they did mosquitoes.
If there were fewer insects that preyed on mosquitoes, that means fewer mosquitoes would die to those insects. This is how the net effect of the birds could have been an increase in mosquitoes, even if the birds did eat many mosquitoes.
D
Since the trees were planted, the annual precipitation has been below average, and drier weather tends to keep mosquito populations down.
This deepens our confusion. If there has been below-average rain after the trees were planted, we’d expect lower mosquito populations. But the mosquito population increased.
E
Increases and decreases in mosquito populations tend to follow a cyclical pattern.
But if we introduce trees that attract birds, and the birds eat many mosquitoes, we’d still expect mosquito population not to increase. Whatever happens generally concerning mosquito populations doesn’t impact what we’d expect to happen after introducing the trees.

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LSAT PrepTest 139 Explanations

Section 1 - Logical Reasoning

Section 2 - Reading Comprehension

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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