Q18 - Until 1985 all commercial airlines

[kimjy89]

I was confused between ansewr choice B and E.

[ManhattanPrepLSAT1]

Great question! I think you're down to the two answer choices that are most tempting.

This question asks us to find an answer choice that is most strongly supported by the information in the stimulus. Answer choice (B) seems to be inferable from the passage as a whole, and answer choice (E) seems to be combining the first, second, and third sentences.

Here's the problem with answer choice (B) - it goes too far. It assumes that all other conditions remain equal. We know of one contributing factor for contracting airborne illnesses. However, there are other potential factors, and while one factor that contributes to the spread of airborne illnesses has increased, it could have been counterbalanced by other factors diminishing the likelihood of contracting such illnesses - such as rules precluding sick people from boarding airplanes.

Answer choice (B) on the other hand must be true given that "the less frequently cabin air is replenished on a flight, the higher the level of carbon dioxide on that flight." It's a singular statement that doesn't rely on any outside assumptions.

(A) is out of scope. We do not know why the airline industry began replenishing the air less frequently. Maybe it was due to a loosening of regulations, but it equally could have been due to some other factor.
(B) relies on unwarranted assumptions about the likelihood that airborne illnesses will be contracted. There are too many other factors that contribute to the likelihood of contracting airborne illnesses and the information in the passage only addresses one such factor.
(C) takes the information in the passage to it's extreme logical opposite position - unfortunately this is unsupported in the stimulus.
(D) goes beyond the information presented. Maybe it was enough to protect the passengers, maybe it wasn't!
(E) controls for other factors by mentioning "similar" flights and only discusses the level of carbon dioxide. This can be directly taken from the third sentence.

I hope this helps you see where answer choice (B) takes a wrong turn. If not, let me know...

[danielalfino]

I also put B instead of E because I had a problem with the fact that E mentions a specific year within the range "prior to 1985." Is it only because the first sentence states that "all commercial airlines" replenished every 30 minutes that we can infer that what happens in any year prior to 1985 is exactly the same? If this sentence instead simply stated that the average rate was 30 minutes, would answer choice E be incorrect?

Thanks.

[ManhattanPrepLSAT1]

Not exactly, but you're on the right track.

We know that in 1980 the level of carbon dioxide in the cabin of a flight had certain characteristics, because we are told in the stimulus that "until 1985 all commercial airlines ..."

So yes, the "all commercial airlines" is critical, but so too is the claim "until 1985." Without that, it would be difficult to make a claim about what happened in 1980.

Without saying both of those things, we could not infer that answer choice (E) is a true statement.

Great question!

[skapur777]

I got this answer correct.

However, what if, for E, there is some other modern development in airplanes that we don't know about that keeps carbon levels down? Or is this controlled by the whole 'similar flights' thing, where similar actually means 'exactly the same'. I'm probably reading too much into it, but that's what the LSAT is amazing at making you do. It says 'similar' but not exact.

[ManhattanPrepLSAT1]

Pay attention to the question stem. It asks for the answer choice that is "most strongly supported" by the information. That's not the same as asking for what "must be true" or what "can be inferred."

The latter two are ones where such a hypothetical should be used to verify the correctness of an answer choice. If you can think of scenarios such as yours on Inference questions, you should be nervous about the answer choice. But for these questions that require a lesser degree of support, be careful about those hypotheticals, because you'll usually be able to find a way in which the answer choice doesn't have to be true!

Does that answer your question?

[ahnhub]

I'm not sure I understand why, if B) is an overstatement, E) is not an overstatement as well.

If we consider that other factors besides the rate of air replenishment in the cabin can affect the likelihood of contracting airborne illness, then we also have to consider that other factors can affect the level of carbon dioxide in the cabin. I don't see how discounting the possibility that people are in general less likely to contract illness today is any different from discounting the possibility that carbon dioxide levels in cabins are generally higher today.

[tamwaiman]

I'm not sure I understand why, if B) is an overstatement, E) is not an overstatement as well.

If we consider that other factors besides the rate of air replenishment in the cabin can affect the likelihood of contracting airborne illness, then we also have to consider that other factors can affect the level of carbon dioxide in the cabin. I don't see how discounting the possibility that people are in general less likely to contract illness today is any different from discounting the possibility that carbon dioxide levels in cabins are generally higher today.

I have the same idea with you, if (B) is overstatement, (E) is not better as well.
However, after reviewing the question, I found (B)'s "people who fly today" is not as TRUE as (E)'s "two-hour commercial airline", which accords with what stimulus refers to "all commercial airlines".

HTH

[ManhattanPrepLSAT1]

Here's what i think is going on, and I'd love to hear what you guys think on this.

The statement says that the less frequently cabin air pressure is replenished, the higher the level of carbon dioxide in that plane and the easier it is for airborne illnesses to be spread.

The subtlety between answer choices (B) and (E) reminds me of the difference between the two tempting answer choices in PT35, S4, Q23. Check out answer choices (A) and (D). And you'll see a strong similarity to the ones here.

For those who don't have that PT, let me put it this way.

The claim about the level of carbon dioxide is absolute. The less frequently the air is replaced the lower the level of carbon dioxide.

Whereas the claim about airborne illnesses is relative in that it would be easier than otherwise, but we don't have a starting point. That's why we have to consider other factors.

Here's an analogy. Answer choice (B) is similar to

"The longer one lays in the sun, the tanner one gets. Jane has laid in the sun longer than Steve. Therefore Jane is tanner than Steve."

This argument fails to consider how tan Jane and Steve were initially.

whereas answer choice (E) is similar to

"The more hamburgers one eats, the more calories one consumes. Will has eaten more hamburgers than Hamid. Therefore Will has consumed more calories than Hamid."

This is direct correlation. The initial starting position is irrelevant.

I get your point about other factors potentially affecting the level of carbon dioxide, but what might those be? The only thing I can think of that would reduce carbon dioxide are plants. And I just don't think of plants when I think of being in an airplane.

[tamwaiman]

Here's an analogy. Answer choice (B) is similar to

"The longer one lays in the sun, the tanner one gets. Jane has laid in the sun longer than Steve. Therefore Jane is tanner than Steve."

This argument fails to consider how tan Jane and Steve were initially.

whereas answer choice (E) is similar to

"The more hamburgers one eats, the more calories one consumes. Will has eaten more hamburgers than Hamid. Therefore Will has consumed more calories than Hamid."

This is direct correlation. The initial starting position is irrelevant.

Hi, I am not sure the analogy of (B) is identical to the stimulus, can someone help to correct me?

The stimulus says, the less frequently replenished, the higher CO2, and the less frequently replenished, the easier it is for airborne illnesses to be spread. Therefore, (B) looks like reasonable: because the less frequently today, the easier it is for illnesses to be spread (unless the easier illnesses-spreading done not means the easier illnesses-contracting.)

THANK YOU

[giladedelman]

Wow, awesome discussion!

First of all, tamwaiman makes an amazing point: "people who fly" is NOT the same as "commercial airlines." Some people fly private planes, some fly in the military, some fly helicopters, etc., etc. ... So we can certainly get rid of (B) on the basis of that unsupported generalization.

However, I also think that Matt's explanation of why (B) is wrong holds up.

See, the stimulus tells us that the less frequently air is replenished, the higher the level of carbon dioxide. Less of this, more of that. Since we know we have less of this (the air is replenished less frequently on post-1985 flights), we can pretty reasonably infer that (higher level of carbon dioxide).

On the other hand, the stimulus only tells us that as carbon dioxide goes up, airborne diseases spread more easily. That is NOT the same as people contracting the diseases at a higher rate. So to get to answer (B), we have to add in one more assumption: that as airborne diseases on airplanes have become more easily spread since 1985, passengers have become more likely to contract them.

----------------------------------

In other words, the stimulus tells us, "Less A --> more B --> more C"

Answer (E) says, okay, we know we have less A than before, so we probably have more B.

But answer (B) says, okay, we know we have less A than before, so we probably have more D. It takes a whole extra step away from the stimulus, and that's the problem.

Does that make this clearer?

[gotomedschool]

Yes it does.

There were two key issues for me that distinguished the right answer: 1-"people who fly today" vs. "all commercial airlines."


The stimulus talks about the replenishment of air in commercial airlines, it doesn't make mention of helicopters, military planes, private jets etc.

2-Correlation is not causation. Just because their is a correlation between carbon dioxide levels and airbone illnesses doesn't mean that there are other factors that could cause/treat airbone illnesses. When I read B, I thought to myself hmmm MAYBEEEEE they are more likely to contract illnesses but probably not or else why would the airlines intentionally expose their customers? Maybe they now release oxygen too? or Airborne illnesses are treatable? I don't know, I just realized that straying this far away from the stimulus meant that the answer choice was likely not the best answer then when I got to E I realized it was the right one.


I won't lie though, I had my answer choice between B and E and one of the features of E that was detracting me was mentioned earlier. It says, the level of carbon dioxide on a two-hour commercial airline flight was lower than it is today on a similar flight. Well what popped into my head was global warming and carbon levels. I know this is somewhat irrelevant but I was thinking hmm maybe if carbon levels are higher today than they were in the past then despite the less frequent replenishing the levels could still be higher.

I went with E anyways though because as you clarified earlier, it's "most strongly supported" not "must be true". I actually wrote this down and hopefully I will pay more attention to details like this in the future.

[vik]

Moreover, the people who fly today could be different from the people who flew in 1980.

[b16]

The above discussion hasn't addressed this point about (E). The answer choice states that it is a "two-hour commercial airline flight."

The stimulus states that pre-1985 the air is replenished every 30 minutes and post-1985 the air is replenished every hour. The answer choice posits a scenario flight time of two hours, which is a multiple of both 30 minutes and 60 minutes. This would imply that the air is equally replenished at the 2 hour point.

The subsequent logic that the cabin would have a higher level of carbon dioxide due to less frequently replenished cabin air should be inapplicable at the 2 hour interval. This should invalidate answer choice (E), yet it is the correct answer according to the LSAT writers.

Is the "two hour" detail actually intended by the LSAT writers as noise that should be ignored, even though it has direct implications on the validity of the answer?

[jamiejames]

I had a slight problem with E because the amount of carbon dioxide on a commercial flight to begin with would be directly linked to the number of people on a flight, so I figured if there were a hundred people on a flight pre 1985, there may be more CO2 on the flight cycling every half an hour than if there was a flight post-1985, with 20 people on it, and the CO2 cycling every hour, that's why I messed this one up and put B instead.

[sportsfan8491]

Every word on the LSAT counts and the key phrase that you really need to pay attention to in this question is "ONCE EVERY (insert temporal factor here)" as this allows us to deduce the correct answer (temporal = time). This tells us that we are looking at a multiple of a time factor. Not having the entire phrase of "ONCE EVERY" down pat and ingrained in your "mind’s eye" before going to the answer choices is a potential recipe for disaster. If you only read it as "every" without the "once" portion, I can how the correct answer might appear deceiving.

Also, just a polite word of caution, but I would be very careful when claiming that the test writers have made a mistake with a credited answer choice. Although not infallible, the Psychometricians creating the LSAT have hardly made any errors on the new era tests. Notice that I qualified my comment by stating that they might not be perfect, but I’d say they have been very, very close to perfect. Mistakes happen, but I do not think that one has occurred in this question or in any of the answer choices in this question.

I apologize if I am repeating other peoples’ points and if my explanation and capitalization of certain words comes across as being overly pedantic, but I think being a little pedantic is important for obtaining a high score on this grueling test.

E) is correct because we are told that the cabin air used to be replenished ONCE EVERY 30 minutes on ALL commercial airline flights until 1985. Remember that this is a multiple of a temporal/time factor and it is a rate/frequency. So, on a two hour flight, the air would be replenished 4 times, no matter how many people were in the plane (I’ve provided some additional comments below to address the quantity of people issue).

Post-1985, the cabin air is only being replenished ONCE EVERY 60 minutes on ALL commercial airline flights. So, on a two hour flight, the air would be replenished 2 times, no matter how many people were in the plane.

To summarize what we have so far in terms of the RATE/FREQUENCY of cabin air replenishment:

Until 1985 _ 4 times
Post 1985 _ 2 times

Given that the FREQUENCY of cabin air replenishment is lower post-1985 (i.e. it is replenished less frequently) we can deduce that there will be a higher level of CO2 in post-1985 flights, so the level must have been lower on a two hour commercial airline flight in 1980.

Understanding the change or delta in terms of frequency is vital for obtaining the correct answer on this question. However, I would personally prefer to stay away from using more complex hypothetical numerical scenarios to gauge the delta or change in the quantity of CO2 because you need to remember that when people breathe, they inherently create CO2 as well (there is a chance that you might not account for all the variables and the LSAT specifically tells you in the instructions that it wants you to be judicious when accounting for all the variables and not make extraneous jumps that are outside the confines of the questions). I want to stress that I’m NOT saying that it’s not appropriate for some questions to use complex hypothetical numerical scenarios, but I would apply the method very judiciously given the time constraints you face.

Another small caveat is that we cannot make extraneous assumptions on how the number of passengers will affect the replenishment cycle, as we are not given any information about how the quantity of passengers specifically affects CO2 levels.

To draw what I think is a relevant parallel to the real world: before and during legal proceedings you would probably want and need to do some detailed research on the more scientific matter of CO2 replenishment in an air plane. That is, you would probably want to account for all of the pertinent variables, say if there was a class action lawsuit from passengers who claimed they got sick on the post-1985 flights. Although this additional information is something you would probably need to consider/address in your future legal career, you would first need to extrapolate what answer choice (E) is telling you before moving on to the more "nitty-gritty" fun research oriented stuff. You need to have the implicit inference that this answer choice provides us before you can validate whether or not what it's telling you is correct. Remember, you cannot build a house without a floor plan and I’d say answer choice (E) is similar to a floor plan.

My intention is not to sound condescending, but I am merely trying to say that you need to stay in the confines of the material, as per the LSAT instructions and read very carefully so that phrases, such as "once every" in this problem, aren't missed or overlooked.

[mahamansoor]

The above discussion hasn't addressed this point about (E). The answer choice states that it is a "two-hour commercial airline flight."

The stimulus states that pre-1985 the air is replenished every 30 minutes and post-1985 the air is replenished every hour. The answer choice posits a scenario flight time of two hours, which is a multiple of both 30 minutes and 60 minutes. This would imply that the air is equally replenished at the 2 hour point.

The subsequent logic that the cabin would have a higher level of carbon dioxide due to less frequently replenished cabin air should be inapplicable at the 2 hour interval. This should invalidate answer choice (E), yet it is the correct answer according to the LSAT writers.

Is the "two hour" detail actually intended by the LSAT writers as noise that should be ignored, even though it has direct implications on the validity of the answer?

I had the same problem... replenish according to the dictionary mean "to bring back to original levels". Therefore, by the 2nd hour both the pre and post 1980 flights would have had the same amount of carbon dioxide on the planes, therefore E would be wrong.

I agree with other posters in that "people who fly today" is out of scope... however, I don't think that E is perfect.

[christine.defenbaugh]

That's a very interesting question that you and b16 raise, mahamansoor!

I think that both of you, though, are fighting the information given to us in the stimulus a bit!

What we know (and must accept as gospel truth) is this:

The less frequently air is replenished, the higher the CO2 level in that plane.

Notice that this doesn't say that the CO2 level is higher at any particular point in time on the plane ride. It also doesn't say that the CO2 level is higher specifically at the instant the flight ends. It merely says, somewhat generally, that the CO2 level is higher 'in that plane'.

Since it's not pointing to a particular, specific moment when you can take a snapshot of the CO2 levels, it would seem to be a general statement about the average or typical CO2 levels when you look at the flight as a whole. Sanity check: it would make more sense to assess the general/typical/average CO2 levels when pointing to how easily airborne illnesses spread; after all, airborne illnesses could be spreading all throughout the flight - they don't wait until the moment the plane lands to jump around!

(E) uses similarly unspecific language - it simply says that the CO2 level for one plane is lower than for another. It doesn't say that the CO2 level at the moment of landing is lower, nor does it point to any other particular moment in time. Just like the information in the stimulus, this seems to be a statement about the general/average/typical CO2 levels in a plane!

Inside the mind of the LSAT Writer: So, why did the LSAT include the detail that this was a 2 hour flight? They needed us to know the flights were the same length. But if they'd just said 'flights of the same duration', we'd have to consider what happens on a 20 minute flight, where presumably no 'replenishing' would occur, so there would be no functional different between pre- and post-1985. So, they need us to know the flights are the same duration, but they are long enough where the difference in replenishing rate actually matters. If they'd said "on a similar flight of the same duration, where that duration is longer than an hour" that would have made us all tear our hair out. I'm sure the easiest way to convey all that information was simply to assign a particular duration that worked.

Be very careful not to over infer from the stimulus OR the answer choice. If (E) were claiming something to be true about the CO2 levels at the instant of landing, it would be very hard to support. A more general statement about the overall CO2 level for the flight is extremely supportable, though, by the general information about overall CO2 levels on flights in the stimulus.

Please let me know if this helps to clear up a few things!

[AlisaS425]

I thought the problem with (B) is that "easier for illnesses to be spread" is different from "people more likely to contract the illness". Just because the illness could be spread easily (maybe it's due to the high level of CO2 or other reasons, we don't know) doesn't mean that people would be more likely to contract the illness (maybe people can take some medicine to prevent it).

Any thoughts?

[YurikaC738]

I thought the problem with (B) is that "easier for illnesses to be spread" is different from "people more likely to contract the illness". Just because the illness could be spread easily (maybe it's due to the high level of CO2 or other reasons, we don't know) doesn't mean that people would be more likely to contract the illness (maybe people can take some medicine to prevent it).

Any thoughts?

I think it is pretty valid to infer easier contraction of airborne diseases based on it is "easier for airborne illnesses to be spread".

The problems with B
1. fly today not equal to all commercial airlines
2. Flight hour can be all below 30 minutes (unrealistically tohugh