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655-705 (Hard)|   Strengthen|                           
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For years the beautiful Renaissance buildings in Palitito have been da 12 Aug 2020, 08:36
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AndrewN
Hahahehe

Hi AndrewN,

I feel everyone is trying to avoid the main question being posed by option E, and just driving the debate towards idling and driving. What we really want to know is, that if at the moment, some buses are driving around because of lack of parking space, then wouldn't building of new parking spaces help, as these buses will be able to park themselves there with engines turned off ?
Hi, Hahahehe. (I typically say "hello," but with your name, I could not resist the wordplay.) I like that you are not taking Expert responses for granted and are choosing instead to write about your concerns. To speak to the point you have brought up, choice (E) presents an unqualified could-be-true scenario: we do not know what may be meant by some. So that we do not lose track of the task at hand, we should examine the question and relevant answer choices again:

Quote:
Which of the following, if true, most strongly supports the argument?
(C) Tour buses typically spend less than one-quarter of the time they are in Palitito transporting passengers from one site to another.
(E) Some of the tour buses that are unable to find parking drive around Palitito while their passengers are visiting a site.

The problem with choice (E), as I see it, is that we cannot make heads or tails of some, and this is a common trap that the GMAT™ question-writers like to employ. As long as we are talking about more than one bus, some would be applicable. But does that necessarily translate to most strongly supporting the argument, namely that damage to Palitito's buildings from the buses' exhaust will diminish significantly? For the sake of argument, let us say that the fleet of tour buses in the Palitito area consists of 1,000 buses. Some could refer to two of them. Maybe these very buses would always be able to park in the assigned parking spaces, but would the damage to the buildings caused by such buses diminish significantly because of it? I am not convinced. Although it could be true that several hundred buses fit into this some, we cannot say for sure. Choice (C), meanwhile, informs us about all tour buses: they typically spend less than one-quarter of the time... so we can deduce that they spend more than three-quarters of the time either parked or idling. The passage goes out of its way to inform us that because of the lack of available parking, most buses have idled at the curb. If parking is expanded to accommodate a third of the tour buses, then, using the same 1,000 buses from before, we now have a guarantee that at least 333 buses will have a place to park at any given time. The GMAT™ likes to deal in certainties, and the reduction in the collective exhaust from these 333 buses is a better bet than the potential reduction from some buses in (E).

Does that make sense? This is a nightmare of a question for the uninitiated, but once you have gone through a gauntlet of such questions and taken the time to unravel them, you emerge much more attuned to the nuances of the test. Thank you again for calling my attention to this one.

- Andrew
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Dear AndrewN,

Haha, I agree, it's a username that probably puts a smile on everyone's face.

Thank you so much for clarifying. This makes complete sense. What I learned is that "some" should be interpreted as "at least one", and that certainly cannot have "significant impact". You are right, the more we practice, more critically we'll be able to evaluate and know the test makers' tricks.

Thank you again for the prompt reply and resolving the confusion :)
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For years the beautiful Renaissance buildings in Palitito have been da 12 Aug 2020, 17:43
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Hahahehe

Dear AndrewN,

Haha, I agree, it's a username that probably puts a smile on everyone's face.

Thank you so much for clarifying. This makes complete sense. What I learned is that "some" should be interpreted as "at least one", and that certainly cannot have "significant impact". You are right, the more we practice, more critically we'll be able to evaluate and know the test makers' tricks.

Thank you again for the prompt reply and resolving the confusion :)
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Nothing wrong with spreading a little cheer. Regarding the question, your takeaways are spot on, and I am glad these answer choices make a little more sense to you now. For another discussion on some, you may want to have a look at my most popular post, here, on a question from the OG 2021.

(I would have responded sooner, but this was my busiest day of work in a long time.)

- Andrew
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hi AndrewN,
I agree that the problem of exhaust from idling buses is not considered.
for me, more tourists choose tour bus than other means of transportation, say subways, that means tourists buses occupy more percentage than subway, so if parking targets to tour buses, then it seems more likely to reduced damage. although D is slightly strengthen, not strong as C, but I think D is just little strengthen.

please point out my fault.

thanks in advance
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For years the beautiful Renaissance buildings in Palitito have been da 05 Apr 2021, 12:29
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zoezhuyan
hi AndrewN,
I agree that the problem of exhaust from idling buses is not considered.
for me, more tourists choose tour bus than other means of transportation, say subways, that means tourists buses occupy more percentage than subway, so if parking targets to tour buses, then it seems more likely to reduced damage. although D is slightly strengthen, not strong as C, but I think D is just little strengthen.

please point out my fault.

thanks in advance
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Hello, zoezhuyan. The main issue I have with (D) is that we are not concerned with how people, tourists or not, arrive in Palitito, only with what the buses are doing within the city, whether driving or idling. Yes, the first line of the passage does indeed say that the buildings in Palitito have been damaged by exhaust from the many tour buses that come to the city. However, the damaging exhaust described thereafter is understood to be emitted once those buses are within the city: idling produces as much exhaust as driving. I would call (D) a good trap answer—it does touch on the presence of tour buses in the city—but this comparison to other means of transportation has nothing to do with the argument, which could hold with or without such a comparison being made. Take, for instance, a split of 35/33/32 for the percent of tourists who visit the city by tour bus, automobile, and train, respectively; we could even make it, say, 23/22/20/18/17 and add planes and ferries to the mix, such that more people could be coming to the city on the whole by other means of transportation, and such a consideration still would not affect the argument.

If you look at choice (C) again, you might notice a clever bit of information that fits the linear logic of the passage perfectly: buses spend so much of the time they are in Palitito driving around, leaving us to deduce that these buses, the ones under scrutiny, must either be idling or be parked the rest of the time. The plan to reduce their exhaust by providing additional parking for a third of the tour bus fleet may not be perfect, but choice (C) directly touches on the argument that damage to Palitito's buildings from the buses' exhaust will diminish significantly. The details make all the difference.

I hope that helps add further clarity to this tough question. Thank you for thinking to ask.

- Andrew
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While I understand how option C is the correct answer, I am unable to eliminate option E.

Some of the buses keep driving around when they can't find parking (driving around creates as much exhaust fumes as idling). So if some of these 'some buses that keep driving around" can find parking in the new system, the amount of exhaust fumes will be reduced.
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While I understand how option C is the correct answer, I am unable to eliminate option E.

Some of the buses keep driving around when they can't find parking (driving around creates as much exhaust fumes as idling). So if some of these 'some buses that keep driving around" can find parking in the new system, the amount of exhaust fumes will be reduced.
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The passage explicitly tells us that idling and driving produce the same amount of exhaust, so whether buses idle at the curb or drive around the city while their tourists are on a tour is really not material.

We want to strengthen the argument that the new parking will SIGNIFICANTLY [quantifiers matter a lot in CR! Keep an eye out for them!] reduce the damage done by bus exhaust.

To strengthen this argument, the first thing I would look for is something that tells me buses can and will use the parking spots.

E just gives us another 'set' of buses that, if they were to use the parking spots, would help us reduce damage done to buildings, but it doesn't strengthen the idea that these buses CAN or WILL use the parking spots!

And none of the answers really provide such a justification! So, drat.

But another, more subtle thing: if buses don't spend that much time *waiting for their tourists* (either idling OR driving around)--if buses spend most of their time shuffling tourists from spot to spot--then these new parking spots won't help enough to *significantly* reduce the damage done to buildings.

Consider this math:

Exhaust from buses driving tourists around + Exhaust from buses waiting for their tourists = total exhaust

This argument is predicated on the idea that we can lower 'exhaust from buses waiting' enough that we will significantly reduce total exhaust. But if that 'exhaust from buses waiting' just isn't very large, this plan won't work!
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elizebethsunny
While I understand how option C is the correct answer, I am unable to eliminate option E.

Some of the buses keep driving around when they can't find parking (driving around creates as much exhaust fumes as idling). So if some of these 'some buses that keep driving around" can find parking in the new system, the amount of exhaust fumes will be reduced.
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(E) doesn't strengthen the argument because it doesn't add meaningfully to what we know.

We already know that most buses are not able to park. The fact that some of those that can't park drive around doesn't make the situation materially different since, as the passage says, "idling produces as much exhaust as driving."

So, regardless of whether waiting buses are idling or driving around, providing parking for a third of them will have the same effect. Thus, the fact that some are driving around doesn't change the expected outcome of the plan.
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For years the beautiful Renaissance buildings in Palitito have been damaged by exhaust from the many tour buses that come to the city. There has been little parking space, so most buses have idled at the curb during each stop on their tour, and idling produces as much exhaust as driving. The city has now provided parking that accommodates a third of the tour buses, so damage to Palitito's buildings from the buses' exhaust will diminish significantly.

Which of the following, if true, most strongly supports the argument?


(A) The exhaust from Palitito's few automobiles is not a significant threat to Palitito's buildings.

(B) Palitito's Renaissance buildings are not threatened by pollution other than engine exhaust.

(C) Tour buses typically spend less than one-quarter of the time they are in Palitito transporting passengers from one site to another.

(D) More tourists come to Palitito by tour bus than by any other single means of transportation.

(E) Some of the tour buses that are unable to find parking drive around Palitito while their passengers are visiting a site.
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­MartyMurray GMATNinja KarishmaB and any other experts

For option (C), how can we deduce that if 1/4 of the time is taken in transporting passengers from one site to another, the remaining 3/4 of the time can only be taken in either parking or idling?
Some other scenarios that can happen:
1. Time spent driving around without any passengers
2. Time spent driving to another place to park the bus before he/she completes his duty

The reason why I eliminated this option is that it seemed to take an assumption that the remaining time can only be spent in either parking or idling. ­
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SlowTortoise

For option (C), how can we deduce that if 1/4 of the time is taken in transporting passengers from one site to another, the remaining 3/4 of the time can only be taken in either parking or idling?
Some other scenarios that can happen:
1. Time spent driving around without any passengers
2. Time spent driving to another place to park the bus before he/she completes his duty

The reason why I eliminated this option is that it seemed to take an assumption that the remaining time can only be spent in either parking or idling. ­
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Regarding, the possibility of 1. Time spent driving around without any passengers, that possibility doesn't change the scenario because, even if they do drive around without passengers, providing more parking will still help to reduce the amount of exhaust they produce while in Palitito.

Regarding 2. Time spent driving to another place to park the bus before he/she completes his duty, the passage is about "tour buses that COME TO THE CITY."

So, presumably, the point is that the buses come to the city with passengers, who tour the city, and then leave with those passengers and drop them off elsewhere at the end of the tour.

Accordingly, 2.Time spent driving to another place to park the bus before he/she completes his duty is out because the drivers would not drive to another place to park the bus while in Palitito. They would do so after leaving Palitito when their tours are complete.­
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Struggled to understand why C stood out.
the portion of pollution from driving: x
the portion of pollution from idling: y
x+y=total pollution from tour buses
if x:y=9:1, then adding more parking lots would not help alleviate total pollution all that much, much of the pollution 90% remains unaddressed
if x:y=1:9, then adding more parking lots sounds a deal
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MartyMurray KarishmaB GMATNinja

(C) Tour buses typically spend less than one-quarter of the time they are in Palitito transporting passengers from one site to another.

This option says 25% time spent going from one site to another, why can't we infer that rest of the time spent on bringing tourist to the city.

Let's say there are 3 sites to visit
Total time = Time to pickup tourist from their location to 1st site + Time travel inside the city from one site another (1 to 2 and 2 to 3rd site) + Time to bring tourist from 3rd site to drop location.

Why rest of the time is considered as parking or idle instead of above case?
We also don't know if the tourist were staying in the same city or different city and just came to visit the site.
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(C) Tour buses typically spend less than one-quarter of the time they are in Palitito transporting passengers from one site to another.

This option says 25% time spent going from one site to another, why can't we infer that rest of the time spent on bringing tourist to the city.

Let's say there are 3 sites to visit
Total time = Time to pickup tourist from their location to 1st site + Time travel inside the city from one site another (1 to 2 and 2 to 3rd site) + Time to bring tourist from 3rd site to drop location.

Why rest of the time is considered as parking or idle instead of above case?
We also don't know if the tourist were staying in the same city or different city and just came to visit the site.
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Notice exactly what choice (C) says:

(C) Tour buses typically spend less than one-quarter of the time they are in Palitito transporting passengers from one site to another.

Choice (C) is about the time when the buses are "in Palitito."

So, "one-quarter of the time" is one-quarter of only the time they are in Palitito. Time spent traveling to Palitito is separate.

So, presumably, during "'the time they are in Palitito," tour buses are transporting passengers, idling, roaming around the city empty, or parked.
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Hi MartyMurray GMATNinja egmat KarishmaB ,

Argument says exhaust emissions (cause) leads to building damage (effect).
Also, reducing the cause (reducing pollution by parking) will lead to reduction in effect (reduce in building damage).
We need to strengthen this.

Choice (B) says that there is no alternate cause leading to the effect.
Hence, IMO (B) should strengthen the author's conclusion.
I completely understand why (C) is correct, but unable to understand why (B) is not strengthener.

Please let me know what am I missing.

Thanks & regards,
Piyush
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For years the beautiful Renaissance buildings in Palitito have been da 08 Sep 2025, 10:45
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Argument says exhaust emissions (cause) leads to building damage (effect).
Also, reducing the cause (reducing pollution by parking) will lead to reduction in effect (reduce in building damage).
We need to strengthen this.

Choice (B) says that there is no alternate cause leading to the effect.
Hence, IMO (B) should strengthen the author's conclusion.
I completely understand why (C) is correct, but unable to understand why (B) is not strengthener.

Please let me know what am I missing.

Thanks & regards,
Piyush
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Getting this question correct takes being precise in reading the passage and identifying the conclusion.

The conclusion is the following:

damage to Palitito's buildings from the buses' exhaust will diminish significantly

Now, what we need to notice to get this question correct is that the conclusion is specifically about "damage to Palitito's buildings from the buses' exhaust."

In other words, the conclusion is not about damage from pollution in general or even damage from exhaust in general. It's about a damage from a specific type of exhaust, "buses exhaust."

Let's now consider choice (B):

(B) Palitito's Renaissance buildings are not threatened by pollution other than engine exhaust.

What we need to see about (B) is that information on whether buildings are threatened by "pollution other than engine exhaust" does not help to confirm that damage from "buses' exhaust" will diminish.

So, (B) has no effect on the strength of the argument.
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The argument deals with only one aspect of the problem: damage caused by exhaust from the tour buses

How is the city trying to reduce this particular damage? The city is giving parking to the tour buses.

The conclusion: damage caused by exhaust from the tour buses will decrease.

So whatever supports it must support that the parking will help reduce damage caused by exhaust from the tour buses.

Any other causes of damage are beyond the scope of our argument. It is certainly possible that exhaust from the tour buses cause only 40% of the yearly damage and 60% is caused by other factors. But this is irrelevant to us. We are currently looking at only 40% of the problem and trying to fix it. The other 60% is someone else's headache.

piyushnagre99
Hi MartyMurray GMATNinja egmat KarishmaB ,

Argument says exhaust emissions (cause) leads to building damage (effect).
Also, reducing the cause (reducing pollution by parking) will lead to reduction in effect (reduce in building damage).
We need to strengthen this.

Choice (B) says that there is no alternate cause leading to the effect.
Hence, IMO (B) should strengthen the author's conclusion.
I completely understand why (C) is correct, but unable to understand why (B) is not strengthener.

Please let me know what am I missing.

Thanks & regards,
Piyush
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piyushnagre99
Hi MartyMurray GMATNinja egmat KarishmaB ,

Argument says exhaust emissions (cause) leads to building damage (effect).
Also, reducing the cause (reducing pollution by parking) will lead to reduction in effect (reduce in building damage).
We need to strengthen this.

Choice (B) says that there is no alternate cause leading to the effect.
Hence, IMO (B) should strengthen the author's conclusion.
I completely understand why (C) is correct, but unable to understand why (B) is not strengthener.

Please let me know what am I missing.

Thanks & regards,
Piyush
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Hi Piyush,

Great question! You're absolutely right that eliminating alternate causes CAN be a strengthener - you know your CR patterns well! The key issue here is understanding what specific claim needs strengthening.

The Critical Distinction:

The argument's conclusion is: "damage to Palitito's buildings from the buses' exhaust will diminish significantly"

This conclusion depends on a crucial assumption: The parking solution will actually reduce the total exhaust produced by buses.

Why (B) Doesn't Strengthen:

Choice (B) tells us that engine exhaust is the only threat to the buildings. But think about what this actually does:

  • It confirms exhaust is a problem ✓
  • It eliminates other threats ✓
  • But does it tell us whether parking 1/3 of the buses will reduce exhaust? ✗


Even if exhaust is the ONLY threat, the parking solution could still fail to reduce exhaust significantly! For example:

  • What if buses only idle for 5 minutes per stop? (Minimal reduction)
  • What if the 2/3 without parking just idle longer? (No reduction)
  • What if most exhaust comes from driving, not idling? (Minimal impact)

Why (C) Actually Strengthens:

Choice (C) tells us buses spend more than 75% of their time NOT driving (i.e., idling at stops). This directly supports that:
  • Idling is a MAJOR source of exhaust (not just driving)
  • Parking 1/3 of buses eliminates a significant portion of total idling time
  • Therefore, total exhaust will reduce significantly

The Pattern You Were Thinking Of:

Your "no alternate cause" pattern works when we're strengthening a causal relationship. For example:

  • "X causes Y, therefore reducing X will reduce Y"
  • Strengthener: "Nothing else causes Y" ✓

But here, we already accept that exhaust causes damage. What we need to strengthen is whether this specific solution (parking) will actually reduce exhaust significantly.

Key Takeaway: Always identify the specific logical gap between premises and conclusion. Here, the gap wasn't "does exhaust cause damage?" but rather "will providing parking actually reduce exhaust significantly?"

Hope this clarifies the distinction! Let me know if you'd like to discuss this further.
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We need something that most strongly supports the argument:-
(A) The exhaust from Palitito's few automobiles is not a significant threat to Palitito's buildings – irrelevant – we are only concerned about bus exhaust
(B) Palitito's Renaissance buildings are not threatened by pollution other than engine exhaust – Irrelevant – They could be or could not be threatenend by other sources.
(C) Tour buses typically spend less than one-quarter of the time they are in Palitito transporting passengers from one site to another – Good Strengthener- for remaining 75% of time, some of the buses can be parked with engine off
(D) More tourists come to Palitito by tour bus than by any other single means of transportation- Irrelevant - we are only concerned about bus exhaust
(E) Some of the tour buses that are unable to find parking drive around Palitito while their passengers are visiting a site. – Irrelevant – as per premise, driving exhaust = idling exhaust

Boil it down:
We have a problem
A solution is provided
Conclusion: the problem will reduce significantly

Gap: The solution helps in reducing the problem
Strengthener: the solution will not intensify the problem
· Anything that provides some mechanism how the solution will reduce problem
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