To decrease the number of crimes in city Y, the city's Police Commissi

OFFICIAL EXPLANATION:

The Police Commissioner's proposal hopes to decrease the number of crimes in city Y by shifting police officers from low-crime to high-crime districts. His proposal is based on data that demonstrate that crime decreases when additional police officers are moved into a district. However, the data do not mention anything about the effect on the districts from which the police officers were removed. The commissioner's plan is based on the assumption that the movement of police officers will not have any adverse effects on the low-crime districts.

(A) While it is encouraging that a similar plan worked successfully in City X, this fact is certainly not essential for the success of the plan in City Y. The cities may be so different as to make the comparison meaningless. (B) The police commissioner's proposal is focused solely on decreasing the number of crimes in city Y. The severity of the crimes has no bearing on whether the commissioner's proposal will succeed or not.

(C) The actual numerical distinction between high and low-crime areas of the city is immaterial to the commissioner's proposal. For instance, if the number of crimes committed in all high crime districts was only double (instead of more than triple) the number of crimes committed in low crime districts, the proposal could still be valid.

(D) It would be practically beneficial to the commissioner's plan if there were more low crime than high crime districts in city Y. This would enable the movement of police officers to every high crime district. However, this is not necessary to achieve the commissioner's goal of decreasing the total number of crimes in city Y. Even if there were more high-crime districts than low-crime districts in city Y, police officers could still be shifted to some (though not all) high-crime districts, and thereby possibly reduce the total number of crimes in city Y.

(E) CORRECT. The police commissioner's proposal would not make sense if districts of the city from which police officers are removed experience significant crime increases shortly after the removal of those officers. This would at least partially, if not fully, negate the reduction in the number of crimes in the high-crime districts. This choice establishes that, in fact, the low-crime districts do NOT suffer from significant crime increases after the removal of some officers-- an essential assumption upon which the commissioner's proposal depends.
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I would go with "E".

We know: (1) Police are trying to decrease crimes. (2) Propose to take police from low crime areas and move to high crime areas. (3) Study shows that additional police = decrease in crimes.

From the given info we can sort of guess that the issue with the plan is that by taking police away from low crime areas, they may in fact see an increase in crimes (b/c the new plan would take additional police away).

I would have to go with (E). The goal is to decrease overall crime levels. If low-crime districts will become high-crime districts following the redeployment of cops, then there is no sense moving cops around, because the overall crime level will be unlikely to decrease.

Now a look at the the other answers:
(A) It certainly helps that there is precedence for success in this type of operation, but this particular plan's success does not depend on this assumption. The plan will automatically fall apart if it wasn't successful in city X.
(B) We're talking about the number of crimes, so I don't think severity has much relevance.
(C) Again, using the negation test (or whatever its called), if this wasn't true, the argument doesn't fall apart.
(D) Again, negation test suggests this doesn't necessary make the argument succeed or fail.

(E) is stronger than any other argument available.

(A) City X experienced a drastic reduction in crime after implementing a proposal similar to that proposed by the Police Commissioner of city Y

if we negate these option choice

City X does not experienced a drastic reduction in crime after implementing a proposal similar to that proposed by the Police Commissioner of city Y

still argument will fall apart because argument clearly states that

"the number of crimes in any district of the city decreases when additional police officers are moved into that district. "

argument clearly uses term "any"
so how can option "A" be wrong..
it also plays a good role of strengthen question.
but after negating it is destroying conclusion as well.

if you negate option A:
City X does not experienced a drastic reduction in crime after implementing a proposal similar to that proposed by the Police Commissioner of city Y

CONCLUSION is there will be reduction in crime and not drastic reduction.
thats why this doesnt shatters the conclusion.

hope this helps

The reason that A is wrong is because it refers to City X, which was never mentioned in the paragraph. The question stem asks us to find the necessary assumption upon which the commissioner's policy for City Y is based. We have no idea about the circumstances of City X's implementation of a "similar" policy; it could be for other reasons that the policy had the intended effect. It really doesn't matter because the circumstances of City X are not necessary for the policy to work in City Y.

The necessary assumption in this case is clearly E, because unless the removal of the police from peaceful areas does not increase the crime rate in those areas, the policy will not work because crime will rise in the originally highly policed areas. In other words, the commissioner is making the necessary assumption that crime free areas will remain crime free, despite losing policing resources to crime filled areas.

Remember, every assumption question refers to a necessary assumption. That means without this assumption the argument will not stand.

A good test for determining necessity is to ask yourself "must this be the case?" Apply this simple method to answer choice A: must it be the case that for City Y's policy to work it also worked for City X? Clearly, this doesn't have to be the case. It is perfectly possible that the policy works in City Y and does not work in City X. Having established that answer choice A is not necessary, we can confidently eliminate it from our choices. If it isn't necessary to the argument, it isn't the correct answer. Apply the same method to E and you will realize that E is necessary for the commissioner's argument to stand.

To decrease the number of crimes in city Y, the city’s Police Commissioner proposed taking some police officers from low-crime districts of the city and moving them to high-crime districts of the city. His proposal is based on city Y crime data that show that the number of crimes in any district of the city decreases when additional police officers are moved into that district. The Police Commissioner’s proposal depends on which of the following assumptions?

• City X experienced a drastic reduction in crime after implementing a proposal similar to that proposed by the Police Commissioner of city Y.
closest to be a wrong ans. there is no talk of city X as the data talks of only city Y
• The severity of crimes committed in any district of the city decreases when additional police officers are moved into that district.
scope shift. it talks of severity not number

• The number of crimes committed in all high-crime districts of city Y is more than triple the number of crimes committed in all low-crime districts of city Y.
nothing related to numbers.. triple?

• There are more low-crime districts than high-crime districts in city Y.
out of scope

• Districts of the city from which police officers are removed do not experience significant crime increases shortly after the removal of those officers.
Correct... the assumption is the areas will not be susceptible to more crime if officers are pulled out

ans E
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The answer is E. If districts from where officers were removed will suffer from high crime, then overall criminal level of the city won't be affected.

A plan will succeed if the solution doesn't inherently create further problems. So the olan is to remove officers from one place to another. Doing so will resuce crime in area that receive additional officers but at the same time won't cause more crime in the area from which offficers are removed.
Option e says the same thing

Posted from my mobile device

To decrease the number of crimes in city Y, the city’s Police Commissioner proposed taking some police officers from low-crime districts of the city and moving them to high-crime districts of the city. His proposal is based on city Y crime data that show that the number of crimes in any district of the city decreases when additional police officers are moved into that district. The Police Commissioner’s proposal depends on which of the following assumptions?

Conclusion lies in the last sentence : the number of crimes in any district of the city decreases when additional police officers are moved into that district
So , to decrease the number of crime they are not just adding more officers to a district. They simply borrow additional officers from other district where crime is low
But this methods decreases the number of police officers in those districts and we have to make sure this does not anyways impact this low crime district

Lets look at (E)
E. Districts of the city from which police officers are removed do not experience significant crime increases shortly after the removal of those officers.

- It says the low crime cities from where officers are removed do not experience crime increase. So , their conditions are stable and not going deteriorate in a while
So the proposal is going to work
Hence Answer is (E)

The plan is to remove police officers from the low crime districts to the high crime districts. Besides it is also stated in the argument that when additional officers are placed in a high crime district the number of crime reduces. The very proposal is based on the assumption the the low crime districts will continue to be low crime districts even after the number of officers decrease. The paraphrase of this statement is in "E". If we work on elimination the "A" states the consequence, "B" talks about severity and not the number of crimes, "C" again gives a consequence and " D" is off context.
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Type- Assumption
Boil it down -Transferring some police officers from low-crime to high crime district will read to decrease in number of crimes in the city Y
"To decrease the number of crimes in city Y, the city’s Police Commissioner proposed taking some police officers from low-crime districts of the city and moving them to high-crime districts of the city "

What if low-crime districts experience a surge in the number of crimes post reduction in police personnel .
If the above scenario is true , then the commissioners' proposal to reduce the number of crimes by transferring police officers will be counterproductive .

Total crime in city Y = number of crimes in district D1(low-crime) .......+ number of crimes in district D2(high-crime)

E. Districts of the city from which police officers are removed do not experience significant crime increases shortly after the removal of those officers. - The argument falls apart on negation of this statement

Answer E
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Answer : E

• City X experienced a drastic reduction in crime after implementing a proposal similar to that proposed by the Police Commissioner of city Y. (This option can be utilized as a strengthner

• The severity of crimes committed in any district of the city decreases when additional police officers are moved into that district.(The paragraph discussed about number of crimes to number of police and not the severity of crimes)

• The number of crimes committed in all high-crime districts of city Y is more than triple the number of crimes committed in all low-crime districts of city Y.(The para does not provides comparison of the high and low crime areas)

• There are more low-crime districts than high-crime districts in city Y.(The para does not provides comparison of the high and low crime areas)

• Districts of the city from which police officers are removed do not experience significant crime increases shortly after the removal of those officers.(This assumption is a permanent solution to reduce crime in City Y

Hope your preparation is going well.
To solve such questions, the first step should be to read the question.
1. The question gives you clarity about the task. In this case, it is asked to identify the assumption. The role of the assumption is to the bridge the gap that exists between premise and conclusion.
2. Next, the argument should be understood.
While reading the argument, the following pattern can be observed
Planning Pattern
Premise – There is a plan to solve the problem.
Conclusion –Do the plan!!
Assumption- there is no problem with the plan
Weakening- Identify problems with the plan
Strengthening- provide solutions to the problems
Let us see the application
The commissioner intends to decrease the number of crimes by moving the police officers from low crime to high crime districts. The proposal of the commissioner is based on the data of city Y which shows that employing additional forces helps to reduce crimes.
.However, the data do not mention anything about the effect on the districts from which the police officers were removed. This is the flaw/gap/loophole present in the argument .The role of the assumption is to bridge this gap. So, in this case it is assumed that movement of police officers will not have any negative effect on the low crime districts and the plan is going to work.
3. The next step is to predict the answer
The plan is going to work or there is no problem with the plan.
4. Eliminate the incorrect choices and reach to the right one
A –This choice is out of scope. The argument nowhere discusses about City X. This analogy is not bridging any gap.
B – The commissioner’s plan intends to reduce number of crimes in city Y .The severity of the crimes is not discussed in the argument. This choice can also be eliminated as it is out of scope.
C-The comparison drawn between high and low crime areas of the city does not influence the commissioner’s decision.
D- This answer choice has no relevance in the discussion and hence is out of scope.
E –This answer choice matches with the predicted answer.

Hope it helps. Please get in touch if you require further help.
Keep practicing.
All the best!!
PythaGURUS Faculty Team
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GMATNinja mikemcgarry daagh chetan2u DmitryFarber

Though I selected E, I still have a doubt.
The goal - decrease in the number of crimes in city Y.
Plan - move police from city X to city Y

Option E addresses the concern regarding the situation in X when police are removed from X.

Even if we negate this , there is still a possibility that there will be a decrease in crimes in CITY Y...

For eg:
I have 10 candies. I want 2 more.
Joe has whatever amount (greater than or equal 2) of candies. I'll take 2 from Joe..
Now why should I care if Joe is left with any candies... My ONLY goal is increase in no. Of candies I possess.

Similarly, the goal here is DECREASE IN NO. of crimes in CITY Y ...even if there crime increases in city X , we may still have a possibility of our goal reaching.

Posted from my mobile device

(A) City X experienced a drastic reduction in crime after implementing a proposal similar to that proposed by the Police Commissioner of city Y. - Out of Scope

(B) The severity of crimes committed in any district of the city decreases when additional police officers are moved into that district. - Out of Scope

(C) The number of crimes committed in all high-crime districts of city Y is more than triple the number of crimes committed in all low-crime districts of city Y. - Out of Scope

(D) There are more low-crime districts than high-crime districts in city Y. - Out of Scope

(E) Districts of the city from which police officers are removed do not experience significant crime increases shortly after the removal of those officers. - Correct

The proposal is to take some police officers from low-crime districts and insert them into high-crime districts. The proposal is intended to decrease the total number of crimes in City Y

What does the proposal, if successful, assume?
A - what is true for others may not be true for Y. Incorrect
B - severity and number of crimes are mutually exclusive. Incorrect.
C - Even if it were triple, if low-crime districts are now unpoliced that may mean crime increases 10x, thus increasing the total number of crimes in the city overall. C is incorrect
D - we are concerned with the number of crimes. We can have 10 low crime districts each with 1 crime each or 5 districts with 2 crimes each, the total number of crimes is the same.
E - is correct. The commissioner must assume that low-crime districts' total number of crimes WONT increase DRAMATICALLY because if it did then the total crime would be greater than before.

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