No. Even with your conclusion, option A will not be weakener. For the following reason:

Let x be the speed limit. If many vehicles drive at 1.25x and we bring down their speed by 20-25%, their new speed will be 0.94x to 1.0x. Thus, their new speed will be within the speed limit.

- Chiranjeev
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generis nightblade354 KarishmaB pikolo2510 GMATNinja GMATninja2

I wonder as to why so many students including me faltered at (C) and if same could be avoided by
more precise reading.

Start with Q:


Plan: installing speed bumps in A -> reduction in traffic speed -> enhancement of safety in residential neighbourhoods of A

I need to prove that in spite of installing speed bumps in A, there might be a decrease in safety index in residential neighbourhoods of A

Let us see the author's reasoning as to why he thinks that installing speed bumps in A shall lead to better safety index in residential neighbourhoods of A



The brute force of limiting vehicle speed to fixed value has been unsuccessful in the town of Ardane.
E.g. a car can only drive to a maximum speed limit of 40 mph so very less chance of accidents.

In nearby towns to A, speed humps (def as provided) have reduced traffic speed by almost a quarter.

So in A too, if we install speed humps then traffic speed will be limited, increasing safety by causing reduction in traffic


I am interested in what happens after installing speed humps. DO NOT CHALLENGE PREMISE in an argument.
Premise is: speed humps are installed.
To doubt: plan of more safe neighbourhood and less traffic will be successful. OUT


How do I link emergency vehicles with the aspect of safety in an argument?


Is this an opposite answer? If residential speed limit in Ardane is higher then after installing speed humps, the speed of
vehicle will decrease. Wait .. what am I supposed to do in this Q?
I am supposed to DOUBT that after installing speed humps safety will decrease, NOT INCREASE as
this choice does.





I rejected (D) and (E) since they cater to very small sub-section of all people mentioned in argument.
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Dear MikunDash,

I'll try to answer your query. kindly follow.
Read the question stem carefully.

Enforcement of local speed limits through police monitoring has proven unsuccessful in the town of Ardane. In many nearby towns, speed humps (raised areas of pavement placed across residential streets, about 300 feet apart) have reduced traffic speeds on residential streets by 20 to 25 percent. In order to reduce traffic speed and thereby enhance safety in residential neighborhoods, Ardane's transportation commission plans to install multiple speed humps in those neighborhoods.



The author wants us to answer with the potential serious drawback to the plan for installing speed humps in ARDANE. Author isn't concerned about the drawbacks in the neighbouring cities. Only concern is Ardane.
I hope this is in itself enough to actually eliminate your query, but if you still need further reinforcement.

The author says that Ardane's transportation commission plans to install multiple speed humps in those neighborhoods.
Multiple jumps off to me from this sentence, may be the neighbouring city didn't install multiple speed humps, hence may be the draw back in the neighbouring city aren't as severe as in Arden.

B. Because of their high weight, emergency vehicles such as fire trucks and ambulances must slow almost to a stop at speed humps.

Just addressing C because it is the second most choose answer option. Also to answer adkikani, "if same could be avoided by more precise reading."
Yes, more precise reading may help you eliminate C. As follows:

Even if residential speed limit in Arden is higher than that of the nearby towns where speed humps were installed. This isn't the potential serious drawback of having speed humps in Arden.

If we read the question carefully, the question mentions potentially serious draw back.

Speed limit is already existent, and potential serious drawback is yet to occur.

I hope this helps us eliminate this answer option as a clear non-contender.

humps reduce speed 20-25%
lets say city has speed 100kmph (speed limit)
now option A says speed is more than 25%
100*(more than 25%)=126kmph(say)
for humps now reduction in speed is 126*0.75=slightly more than 100kmph
again it violates speed limit then why is option A is not an answer

Official Answer is B, and I kind of understand why. Can experts please explain why the argument's goal changed from limiting the speed to safety of lives and property.

Argument:
enforcement of speed limits is of no use. After looking at the nearby town,the speed-humps managed to reduce the traffic speeds,so Ardanes transportation commission plans to install MULTIPLE SPEED-HUMPS.

we have to find a serious draw back of the plan

A. On residential streets without speed humps, many vehicles travel at speeds more than 25 percent above the posted speed limit. (this infact does not show any flaw rather its the opposite)

B. Because of their high weight, emergency vehicles such as fire trucks and ambulances must slow almost to a stop at speed humps. (so emergency vehicles will slow almost to a stop at MULTIPLE speed-humps. hmmm thats gonna delay the services big time!!!! imagine there are 10 speed humps the fire truck will have to stop 10 times so it clearly is a FLAW.

C. The residential speed limit in Ardane is higher than that of the nearby towns where speed humps were installed.
(irrelevant)

D. Motorists who are not familiar with the streets in Ardane's residential districts would be likely to encounter the speed humps unawares unless warned by signs and painted indicators.(the statement itself gives the solution as well lol)

E. Bicyclists generally prefer that speed humps be constructed so as to leave a space on the side of the road where bicycles can travel without going over the humps.(irrelevant)

So this question wants us to choose the answer that "identifies a potentially serious drawback to the plan for installing speed humps". In other words, which answer choices shows why it is a BAD idea to have speed bumps?

(A) has nothing to do with why speed bumps would be bad. If anything, A gives us a good reason why there SHOULD BE speed humps.

The passage tells us "In many nearby towns, speed humps ... have reduced traffic speeds".So that indicates that speed humps ARE effective. A is talking about streets without the humps. A says: On streets without humps, people go too fast.
How does that "identify a serious drawback to the plan for installing speed humps"?
It doesn't --- it's not related to what the question is asking us to do

In a serious drawback question, should we be looking for a bad assumption or something that weakens the conclusion?

At first glance, I thought of this question as a 'weaken' type. Since argument used in the article is analogy, to weaken it should be to point out the difference between two subjects, Ardane town and nearby town, and thus C is correct.

But later I noticed that the question is to choose the drawback. So we need only point out a drawback of the measure itself, then B is better.

Is my idea correct ?

GMATNinja please provide why C is not a drawback in the argument ??

According to the passage, Ardane’s transportation commission develops a plan to install speed humps “in order to reduce traffic speed and thereby enhance safety in residential neighborhoods.” The question asks that we identify a drawback to that plan. Consider (C):


If speed humps effectively reduced traffic speed where speed limits were lower (and drivers were presumably driving slower), then similar speed humps will almost certainly reduce driving speeds where speed limits are higher (and drivers are presumably driving faster). This means that the plan is very likely to achieve its goal of reducing traffic speeds.

(C) would require far too many assumptions and far too much additional information to even hint at a drawback. For example, some may argue that the plan could potentially reduce traffic speeds too much, but we have no information to indicate by how much the speed limit in Ardane differs from that of nearby towns. If the residential speed limit is merely 5 mph higher, then any negative impact on the flow of traffic will likely be negligible. Therefore, (C) does not indicate a drawback, and we can eliminate it.

I hope that helps!
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Hi I must say that I am not satisfied with the reasons given for B...first of all thinking about the wording in the passage, it says that firetrucks and ambulances ALMOST have to come to a stop, but that does not suggest that they do. It is also perfectly reasonable to think that ambulances and firetrucks are familiar with the best routes for getting to a location (one would hope). Looking out in my neighbourhood, fire trucks and ambulances seem to move along just fine. Things like traffic are stronger barriers than a hump here and there.

D - many have argued that you can just 'put up a sign'. That seems way too convenient to me. There is a clear concern about safety here motorists who are unaware of the sign can certainly get into an accident.
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Our ask is to find a flaw in the plan of installing humps. Why is there a need of installing humps --> To reduce speed & enhance safety.

How on earth does slowing down ambulances and emergency vehicles' indicates a flaw in the plan? Ok, I'll agree that the speed got reduced. What about enhancing safety?

What about bikers? They are failing both the objectives of the plan:
1. No speed is reduced as stated in the passage -- Unaware
2. Safety is at risk.

Even if we assume that the emergency vehicles have the potential to enhance safety. Aren't we assuming way too much?

GMATNinja or any experts, please help.
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It's important to notice the exact language of the question -- here, we are not asked to find a flaw in the logic of the plan. Instead, we have to identify a "potentially serious drawback" to installing speed humps. (Side note: do people actually call these speed humps? I've always heard speed bumps. )

So we don't specifically need to determine why the humps would not reduce speed or increase safety. We're looking for ANY potential drawback to installing speed humps in the town -- maybe speed humps severely damage the bottoms of cars, or maybe thieves wait in the woods and carjack people who slow down at the speed humps. There doesn't HAVE to be a connection between the "drawback" and the intended goal of installing the speed humps.

With that in mind, consider (B):

This is a serious drawback! Emergency vehicles need to move quickly to put out fires and get injured people to the hospital. If the vehicles have to slow down almost to a stop, then the town of Ardane might, on the whole, suffer if the plan to install speed humps is implemented.

(B) identifies a drawback to installing speed humps, so it's the correct answer.

Take another look at (E):

(E) tells us about what kind of speed humps would be preferred by bicyclists. But it doesn't tell us that this kind of speed hump will actually be installed. So we really can't conclude that (E) gives us any information that would impact speed or safety.

In addition, even if the speed humps with space on the side ARE installed, (E) still doesn't identify a serious drawback to installing speed humps. Maybe these speed humps are slightly less effective at reducing speed than other speed humps would be, but overall, the speed humps would still be somewhat effective and there isn't really a downside to installing them.

(E) is out because it doesn't identify a serious drawback to installing speed humps.

I hope that helps!
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