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555-605 (Medium)|   Inference|                              
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AjiteshArun
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Humans get Lyme disease from infected ticks. Ticks get infected by 02 Feb 2024, 21:59
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PReciSioN
Hi Ajitesh,

Thanks for your response! I went over your course video too and found it helpful! So I infer from the video (pun intended haha), that in the "MUST BE TRUE" category of questions, only the questions which explicitly mention - "MUST BE TRUE" are the water-tight questions and questions like "most strongly support" leave some wiggle room.
Do questions like "which of the following can be properly concluded/ inferred" etc also leave some wiggle room?
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Hi PReciSioN,

That's correct. On the GMAT, you're almost always going to get the phrase "must be true". As for the other stems (more likely to be seen on exams like the LSAT), (a) "can be properly concluded/inferred" and (b) "logically follows" are also must be true questions.

Also, we should check whether the stem refers to the options (as you mentioned, "which of the following can be properly concluded..."), because we can see similar language in necessary assumption questions.
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Humans get Lyme disease from infected ticks. Ticks get infected by 05 Feb 2024, 03:45
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AjiteshArun

PReciSioN
Hi Ajitesh,

Thanks for your response! I went over your course video too and found it helpful! So I infer from the video (pun intended haha), that in the "MUST BE TRUE" category of questions, only the questions which explicitly mention - "MUST BE TRUE" are the water-tight questions and questions like "most strongly support" leave some wiggle room.
Do questions like "which of the following can be properly concluded/ inferred" etc also leave some wiggle room?
Hi PReciSioN,

That's correct. On the GMAT, you're almost always going to get the phrase "must be true". As for the other stems (more likely to be seen on exams like the LSAT), (a) "can be properly concluded/inferred" and (b) "logically follows" are also must be true questions.

Also, we should check whether the stem refers to the options (as you mentioned, "which of the following can be properly concluded..."), because we can see similar language in necessary assumption questions.
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Understood. Thank you so much Ajitesh!! :)
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Humans get Lyme disease from infected ticks. Ticks get infected by 06 Feb 2024, 11:52
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PReciSioN

So I infer from the video (pun intended haha), that in the "MUST BE TRUE" category of questions, only the questions which explicitly mention - "MUST BE TRUE" are the water-tight questions and questions like "most strongly support" leave some wiggle room.
Do questions like "which of the following can be properly concluded/ inferred" etc also leave some wiggle room?
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Those questions generally do not "leave some wiggle room."

The ones that say most strongly supported BY generally "leave some wiggle room."

The ones that say PROPERLY inferred or concluded FROM generally do not.
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Humans get Lyme disease from infected ticks. Ticks get infected by 07 Feb 2024, 02:16
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MartyMurray

PReciSioN

So I infer from the video (pun intended haha), that in the "MUST BE TRUE" category of questions, only the questions which explicitly mention - "MUST BE TRUE" are the water-tight questions and questions like "most strongly support" leave some wiggle room.
Do questions like "which of the following can be properly concluded/ inferred" etc also leave some wiggle room?
Those questions generally do not "leave some wiggle room."

The ones that say most strongly supported BY generally "leave some wiggle room."

The ones that say PROPERLY inferred or concluded FROM generally do not.
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­Perfect! Thanks a ton Marty! :) 
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Humans get Lyme disease from infected ticks. Ticks get infected by 13 Aug 2024, 20:04
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Hi ik it has been discussed but I like to super sure why this reasoning and option is incorrect -
For option D) Why cant we say it is correct because if it were incorrect it would mean that Ticks feed on White mice even when they have other species available to them aka biodiversity is not in decline/high and doesn't that then weakens the info given?

Some answers said that we don't know about feeding preferences of ticks but we do know the preference in case of other species not available implying biodiversity in decline.

So is the actual reason why D is out is because - The wording in option is very emphatic - Ticks feed on WF only when other species not available, however it maybe true that they might continue to feed atleast on a few if not a lot even when other species are available. This way info in stem is also honoured and option eliminated.­

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Humans get Lyme disease from infected ticks. Ticks get infected by 15 Aug 2024, 08:01
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Kavicogsci
Hi ik it has been discussed but I like to super sure why this reasoning and option is incorrect -
For option D) Why cant we say it is correct because if it were incorrect it would mean that Ticks feed on White mice even when they have other species available to them aka biodiversity is not in decline/high and doesn't that then weakens the info given?
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The passage says only the following about white-footed mice:

And white-footed mouse populations greatly expand, becoming the main food source for ticks, in areas where biodiversity is in decline.

Notice that it says only that white-footed mouse populations "expand" when biodiversity is in decline.

That information does not mean that white-footed mice do not exist at all when biodiverisity is not in decline.

So, even when biodiversity is not in decline, ticks could feed on white-footed mice. In other words, ticks could feed on white-footed mice even when other species are available for feeding on.
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So is the actual reason why D is out is because - The wording in option is very emphatic - Ticks feed on WF only when other species not available, however it maybe true that they might continue to feed atleast on a few if not a lot even when other species are available. This way info in stem is also honoured and option eliminated.­
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­Yes, that's the reason to eliminate (D).
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Humans get Lyme disease from infected ticks. Ticks get infected by 17 Aug 2024, 04:56
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What is to say that in areas with high biodiversity, WF mice are not major source for feeding ticks?
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Humans get Lyme disease from infected ticks. Ticks get infected by 17 Aug 2024, 15:24
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Shaileen
What is to say that in areas with high biodiversity, WF mice are not major source for feeding ticks?
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­They could be, as Marty addresses in the post above. However, the passage tells us that the mice *become* the main food source when biodiversity is in decline, so they must not typically be the main food source. If they go from feeding 40% of ticks to feeding 65% of ticks, that would still support C.
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Humans get Lyme disease from infected ticks. Ticks get infected by 07 Nov 2024, 04:19
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Isnt A and C similar?

See, A says that
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Humans get Lyme disease from infected ticks. Ticks get infected by 07 Nov 2024, 04:25
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WillGetIt
Humans get Lyme disease from infected ticks. Ticks get infected by feeding on animals with Lyme disease, but the ease of transmission from host animal to tick varies. With most species of host animal, transmission of Lyme disease to ticks is extremely rare, but white-footed mice are an exception, readily passing Lyme disease to ticks. And white-footed mouse populations greatly expand, becoming the main food source for ticks, in areas where biodiversity is in decline.

The information in the passage most strongly supports which of the following?

(A) In areas where many humans are infected with Lyme disease, the proportion of ticks infected with Lyme disease is especially high.

(B) Very few animals that live in areas where there are no white-footed mice are infected with Lyme disease.

(C) Humans are less at risk of contracting Lyme disease in areas where biodiversity is high.

(D) Ticks feed on white-footed mice only when other host species are not available to them.

(E) The greater the biodiversity of an area, the more likely any given host animal in that area is to pass Lyme disease to ticks.

ID - CR04986


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Ticks and Lyme Disease

Step 1: Identify the Question

The question states that the information in the passage will support a particular answer choice. That indicates an Inference question.

Step 2: Deconstruct the Argument

ticks feed on animals w/ Lyme, ticks give Lyme to humans

trans. from animal → tick:

- usually rare

- common w/ WF mice

less biodiversity → ticks mostly feed on WF mice

Because this is an Inference problem, there is no conclusion in the argument. Instead, the argument states a series of facts. Lyme is transmitted from animals to ticks to humans. White-footed mice are likely to give Lyme to ticks, while other animals aren’t. Also, ticks feed more on white-footed mice in areas with less biodiversity.

Step 3: Pause and State the Goal

In an Inference problem, the right answer will be something you can prove to be true using only the information in the argument. Identify one answer that can be proven true, and four answers that are not necessarily true.

Step 4: Work from Wrong to Righti

(A) This seems reasonable, because the argument states that humans get Lyme disease from infected ticks. However, is it necessarily true that if there are many infected humans in an area, there must be a high proportion of infected ticks in the area? There are at least two scenarios in which this isn’t true. Perhaps many people in one place contract Lyme disease while on vacation, even though there are no infected ticks where they live. After they return home, there could be many people with Lyme disease in a particular area, but no infected ticks. Also, there could be a relatively small proportion of infected ticks in an area, but humans could be bitten by infected ticks at an unusually high frequency. Perhaps there are just a lot of ticks meaning that even a small proportion that are infected may lead to a lot of Lyme disease in humans. Alternatively, people in these areas may encounter ticks (e.g. go hiking a lot) more frequently than people in other areas.

(B) According to the logic of the argument, if there are no white-footed mice in an area, transmission of Lyme disease from host animals to ticks should be very rare. However, this does not imply that other animals—aside from ticks—don’t have Lyme disease. It just implies that ticks don’t get Lyme disease from them, regardless of whether they have it. The argument doesn’t describe the way that the host animals get Lyme disease in the first place, so they could have contracted Lyme from some other source.

(C) CORRECT. Since ticks only get Lyme disease from other animals extremely rarely, the odds that a tick will carry Lyme disease is directly related to how often it feeds on white-footed mice. In areas with low biodiversity, white-footed mice are relatively more common. Therefore, in areas with more biodiversity, white-footed mice will be relatively less common, and ticks will feed on them less frequently. The ticks in these areas will be less likely to have Lyme disease. In areas with a smaller proportion of Lyme-infected ticks, humans will be at less risk of contracting the disease.

(D) The argument states that when white-footed mouse populations greatly expand, they become the main food source for ticks. However, the argument doesn’t specify what happens when white-footed mouse populations are relatively low. It’s possible that ticks would still regularly feed on white-footed mice, even if other host species are present.

(E) This is untrue, according to the argument. In areas of greater biodiversity, white-footed mice are relatively less common. White-footed mice are much more likely than other animals to transmit Lyme to ticks. With fewer white-footed mice, the average animal will actually be less likely to transmit Lyme to ticks.
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Isnt A and C similar?
A) In areas where many humans are infected with Lyme disease, the proportion of ticks infected with Lyme disease is especially high.
Humans are infected with Lyme the proportion of ticks infected shouldn't necessarily be high. even with few ticks many people can get infected

(C) Humans are less at risk of contracting Lyme disease in areas with high biodiversity.
Humans are at less risk of contracting high. We can even use the logic above that
Biodiversity high, White mice low, so ticks low.

But still WITH FEW TICKS many people may still be at risk of getting infected with Lyme right??
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Humans get Lyme disease from infected ticks. Ticks get infected by 08 Nov 2024, 13:51
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anushridi

The important difference is that C is only making a relative statement. Biodiversity makes it less likely for humans to contract Lyme disease than would otherwise be the case. This fits the pattern we might see with a weaken question. If someone argues that X will happen because of Y, we can weaken the argument by providing a new fact that makes Y seem unlikely to happen. That doesn't mean that X won't happen at all, or even that Y won't happen. It just weakens the idea that X will happen.

It's kind of the same thing here. There are many reasons that we could still get Lyme disease. If there's high biodiversity in an area, maybe white-footed mice are still common and so there are a lot of ticks contracting Lyme disease from them. Or maybe there are so many ticks that transmission is fairly common in the area. Or maybe some other species that thrives under high diversity is able to pass the disease to ticks in this area. Maybe there are people who seek out ticks and put themselves at risk! I could go on like this for quite some time. But C doesn't tell us that Lyme will be rare, just that it will be less common than it would otherwise be, so the assertion isn't really saying that much--exactly what we want from an inference answer!
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Humans get Lyme disease from infected ticks. Ticks get infected by 15 Nov 2025, 08:37
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