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When mercury-vapor streetlights are used in areas inhabited by insect-

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When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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Which of the following most logically completes the argument below?

When mercury-vapor streetlights are used in areas inhabited by insect-eating bats, the bats feed almost exclusively around the lights, because the lights attract flying insects. In Greenville, the mercury-vapor streetlights are about to be replaced with energy-saving sodium streetlights, which do not attract insects. This change is likely to result in a drop in the population of insect-eating bats in Greenville, since __________.

(A) the bats do not begin to hunt until after sundown

(B) the bats are unlikely to feed on insects that do not fly

(C) the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights

(D) in the absence of local concentrations of the flying insects on which bats teed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat

(E) bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night
[Reveal] Spoiler: OA

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Re: When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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New post 29 Nov 2015, 07:34
Steinbeck wrote:
Which of the following most logically completes the argument below?

When mercury-vapor streetlights are used in areas inhabited by insect-eating bats, the bats feed almost exclusively around the lights, because the lights attract flying insects. In Greenville, the mercury-vapor streetlights are about to be replaced with energy-saving sodium streetlights, which do not attract insects. This change is likely to result in a drop in the population of insect-eating bats in Greenville, since ___________________________________

(A) the bats do not begin to hunt until after sundown
(B) the bats are unlikely to feed on insects that do not fly
(C) the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights
(D) in the absence of local concentrations of the flying insects on which bats teed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat
(E) bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night


Mercury-vapor streetlights----> Attracts insects -----> Bats prey on them around the lights (at a single location)

No Mercury-vapor streetlights -----> No insects around the lights -------> Drop in population of bats

So, how does Bats survive ? Does they stop eating insects ? Probably not , they must be hunting the insects anyway for survival.



(A) the bats do not begin to hunt until after sundown - Talks about sundown , but doesn't account for the Bats food and reduced population.

(B) the bats are unlikely to feed on insects that do not fly - Out of scope.

(C) the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights - Talks about replacement of llights and not about the reduction in population of bats.

(D) in the absence of local concentrations of the flying insects on which bats teed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat - This can be a cuse for reduction of Bats population.

(E) bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night - Out of scope.

Hence answer is (D)
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Re: When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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New post 22 Dec 2015, 15:37
Steinbeck wrote:
Which of the following most logically completes the argument below?

When mercury-vapor streetlights are used in areas inhabited by insect-eating bats, the bats feed almost exclusively around the lights, because the lights attract flying insects. In Greenville, the mercury-vapor streetlights are about to be replaced with energy-saving sodium streetlights, which do not attract insects. This change is likely to result in a drop in the population of insect-eating bats in Greenville, since ___________________________________

(A) the bats do not begin to hunt until after sundown
(B) the bats are unlikely to feed on insects that do not fly
(C) the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights
(D) in the absence of local concentrations of the flying insects on which bats teed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat
(E) bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night

We need to find an explanation why population of bats will decline
A is wrong since time of hunt is not a factor. What if bats begin after sundown? It doesn't explain why population will decline
B is wrong since it doesn't explain why population will decline (only says what kind of insects bats prey on)
C is out of scope
D is correct. If bats spend more energy and require much larger quantities of insects to sustain each bat then the same number of insects will be available for fewer bats (competiton increases=))
E is out of scope
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Re: When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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New post 26 Jan 2016, 21:21
according to the OG online results screen, this Q is a Medium difficulty level. Please update to reflect

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Re: When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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New post 29 Apr 2016, 05:22
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Keats wrote:
Which of the following most logically completes the argument below?

When mercury-vapor streetlights are used in areas inhabited by insect-eating bats, the bats feed almost exclusively around the lights, because the lights attract flying insects. In Greenville, the mercury-vapor streetlights are about to be replaced with energy-saving sodium streetlights, which do not attract insects. This change is likely to result in a drop in the population of insect-eating bats in Greenville, since ___________________________________

(A) the bats do not begin to hunt until after sundown
(B) the bats are unlikely to feed on insects that do not fly
(C) the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights
(D) in the absence of local concentrations of the flying insects on which bats teed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat
(E) bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night


Respoding to a PM,

lets see the PARA-
Bats feed EXCLUSIVELY on the insects around the street light. These street lights are now being converted to some other form which does not attract light.
The conclusion is "This change is likely to result in a drop in the population of insect-eating bats" and we have to complete the statement citing some reason for it..


What are you required to do- Give reasons for the conclusion..

What does it ask you to do?
Your answer has to be -
1) firstly related to some info existing in the PARA.
2) secondly it has to be strengthening the conclusion.


lets see the choices for these two points-

(A) the bats do not begin to hunt until after sundown
Does it give reason to strengthen our conclusion. NO..

(B) the bats are unlikely to feed on insects that do not fly
Again nothing .. the point would be same for any kind of street lights..

(C) the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights
It does not follow any of our 2 points
Out of context


(D) in the absence of local concentrations of the flying insects on which bats teed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat
Now this is related to change over of lights..
Also that word in capitals EXCLUSIVELY tells us that they were having easy meals. But this changeover has resulted in two things-
a) Lesser avail of insects in close proximity
b) spending extr aenergy for food and in turn requiring MORE food. likely that the strength will go down
PERFECT as an answer


(E) bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night
again Not related to the conclusion
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Re: When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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When Mercury vapor street lights were used - Bats fed insect around the light
Mercury vapor streetlights are now replaced by sodium streetlights - Does not attract insects - Bats population will drop

We have to select an answer choice that will provide the reason for the drop in bat population

(A) the bats do not begin to hunt until after sundown - Incorrect - Irrelevant

(B) the bats are unlikely to feed on insects that do not fly - Incorrect - Rather than providing the reason for the decline in bat population this option tries to attack the fact stated in the argument.

(C) the highway department will be able to replace mercury-vapor streetlights with sodium streetlights within a relatively short time and without disrupting the continuity of lighting at the locations of the streetlights - Incorrect - Irrelevant

(D) in the absence of local concentrations of the flying insects on which bats feed, the bats expend much more energy on hunting for food, requiring much larger quantities of insects to sustain each bat - Correct - Suppose there were 100 bats and 100 insects, earlier 1 bat required 1 insect. Because the light does not attract insects bats spend more energy now. So 1 bat requires 2 insects. 100 insects is sufficient for only 50 bats. Other 50 will starve to death, resulting in population decline.

(E) bats use echolocation to catch insects and therefore gain no advantage from the fact that insects flying in the vicinity of streetlights are visible at night - Incorrect - Again attacks the fact stated in the argument

Answer: D

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Re: When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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New post 14 Mar 2017, 15:16
Strenghten question: we are looking for answe that will tell us about the bats population at risk connected with the lights replacements

D is the one that fits

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Re: When mercury-vapor streetlights are used in areas inhabited by insect- [#permalink]

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New post 18 Aug 2017, 03:22
Correct choice is 'D' - Since there will be no local concentrations of flying insects around Greenville streetlights after the change, the bats will most likely have more trouble getting enough to eat, and that their local population will therefore fall.
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Re: When mercury-vapor streetlights are used in areas inhabited by insect-   [#permalink] 18 Aug 2017, 03:22
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