12 Days of Christmas GMAT Competition - Day 3: In the country of Xant

Question

12 Days of Christmas GMAT Competition with Lots of Fun

In the country of Xantharu, only 10% of children have experienced lactose intolerance episodes that were severe enough to require medical attention. However, in the neighboring country of Tripania, 30% of children have never experienced lactose intolerance episodes that required medical attention. Therefore, the inhabitants of Xantharu must be better adapted to digest lactose, found in dairy products commonly consumed by children, such as cow’s milk, than are the inhabitants of Tripania.

Which of the following is an assumption on which the argument depends?

(A) On average, each child in Xantharu is not consuming more cow’s milk daily than each child in Tripania.

(B) Children in Xantharu are not more likely to consume lactose-free milk alternatives than are children in Tripania.

(C) In Xantharu, only 20% of adults and teens experience severe lactose intolerance, compared to 40% of adults and teens in Tripania who experience severe lactose intolerance.

(D) The population size of Xantharu is comparable to the population size of Tripania.

(E) The rate of severe lactose intolerance among children in Xantharu has been lower than the rate in Tripania for over three generations.

Bunuel · Accepted Answer

Manhattan Prep Official Explanation

Step 1: Identify the Question

The words  assumption  and  on which the argument depends  in the question stem indicate that this is a Find the Assumption question.

Step 2: Deconstruct the Argument 
 
The author tells you about two countries: Xantharu (X) and Tripania (T). In X, only 10% of children have experienced severe lactose episodes, whereas in T, 70% of children have. (Note the reverse wording for T that makes it easy to read the percentage incorrectly!) The author concludes that the inhabitants of X are less intolerant of lactose than the inhabitants of T—while also working in the fact that lactose is found in dairy products that are commonly consumed by children (for example: cow’s milk).

Step 3: Pause and State the Goal 
 
Look for an assumption that the author must believe to be true for the argument to work.

In this argument, the author is relying on statistics of severe lactose reactions to indicate that there is a lower rate of lactose intolerance in X. However, perhaps inhabitants of X are disincentivized to seek medical attention for cases of severe lactose intolerance, resulting in data that presents an inaccurate story. Alternatively, perhaps X has more effective medications to treat lactose intolerance (and so prevent severe reactions) or medications that are more readily available than medications available in T. Or maybe children in X don’t consume as many lactose-based products as children in T in the first place.

Step 4: Work From Wrong to Right

(A) This is a great trap; it’s the opposite of what the author actually assumes. In drawing a comparison between X and T, the author starts from the baseline assumption that it is not the case that children in X simply don’t consume as much lactose. Take this to an extreme: If 90% of X children have never consumed lactose in the first place, then 100% of the ones who did consume lactose exhibited a serious intolerance! That kills the author’s argument. So the author is assuming that the reason the T kids have more reactions is not because they’re more likely to consume a lactose-containing product in the first place—but this choice says the opposite of that.

(B) CORRECT.  This one is negatively worded, making it tougher to understand. Basically, it’s stating that the author assumes that both children in X and children in T are equally likely to consume lactose-based products.

A technique known as Negation can help you understand negatively-worded answer choices on Assumption problems (but don’t use this on other CR problem types).To use Negation, take out the negative word and reread the choice. What happens to the argument? If the answer choice is truly an assumption, then it is necessary to the argument, so negating it will make the argument fall apart:

Children in Xantharu ARE not more likely to consume lactose-free milk alternatives than are children in Tripania.

If children in X are more likely to consume lactose-free milk alternatives than are children in T, then inhabitants of X may not have a greater tolerance to lactose than inhabitants of T. Rather, some of them may simply not be consuming lactose in the first place.

(C) This answer choice provides information about additional age groups in X and T, specifically adults and teens. If adults and teens in T experience higher rates of severe lactose intolerance than adults and teens in X, that certainly strengthens the author’s argument. However, the numbers listed here are very specific—too specific to be necessary to the author’s argument. The author doesn’t need to assume these specific percentages in order for the argument to work.

(D) The argument mentions only percentages, which indicate a relationship of a subgroup (those who experience severe lactose intolerance) to the main group. Regardless of how large the population is, these percentages remain the same. For example, it doesn’t matter whether X has a population of 1,000 children and 100 experience severe lactose intolerance or whether X has a population of 10,000 and 1,000 of them experience severe lactose intolerance—either way, it’s still 10% of the population.

(E) Like answer (C), this choice is too specific. While the author’s argument does seem to assume that inhabitants of X adapted to have greater lactose tolerance, the author never claims a specific time frame during which that adaptation must have occurred.

ElninoEffect · Answer

Assumption  question calls for a pre-thinking approach.

Conclusion:  the inhabitants of Xantharu must be better adapted to digest lactose, found in dairy products commonly consumed by children, such as cow’s milk, than are the inhabitants of Tripania.

Prethinking:  Under what conditions inhabitants of Xantharu are not better adapted to digest lactose than are the inhabitants of Tripania, given that 
only 10% of children have experienced lactose intolerance episodes in Xantharu and 70% of the children have experienced lactose intolerance episodes in Tripania.

Case1: what if the inhabitants of Xantharu drink more lactose intolerant milk than lactose milk.
Case2: what if only a small portion of the people suffering from lactose intolerance has been reported in Xantharu.

So the assumptions are:
Case1: the inhabitants of Xantharu do not drink more lactose intolerant milk than lactose milk.
Case2: All the people suffering from lactose intolerance are reported in Xantharu.

Now lets see the options:

(A) On average, each child in Xantharu is not consuming more cow’s milk daily than each child in Tripania. 
 Not in line with our pre-thinking approach.
Also, no relation has been found between the quantity of milk consumption and intolerance.

(B) Children in Xantharu are not more likely to consume lactose-free milk alternatives than are children in Tripania. 
 Exactly in line with our pre-thinking approach.

(C) In Xantharu, only 20% of adults and teens experience severe lactose intolerance, compared to 40% of adults and teens in Tripania who experience severe lactose intolerance. 
 Not in line with our pre-thinking approach. + We are concerned with people in total not what portion of the segment.

(D) The population size of Xantharu is comparable to the population size of Tripania. 
 Not in line with our pre-thinking approach. + We are dealing with percentages, not numbers. If it would have the numbers instead of percentage it would have mattered.

(E) The rate of severe lactose intolerance among children in Xantharu has been lower than the rate in Tripania for over three generations. 
 Not in line with our pre-thinking approach.

JulienC · Answer

Statements:
10% of children in Xantharu have experienced  severe  lactose intolerance episodes
70% of children in Tripania have experienced lactose  severe  intolerance episodes (30% haven't => 70% have)
Argument:
Xantharu  must  be better adapted to digest lactose than are the inhabitants of Tripania
(note the argument states that Xantharu  inhabitants  (not just children) are better adapted.

Assumptions I can think of:
1) the adult population has the same rate of severe lactose intolerance as the children
2) The % of citizens in both populations that have consumed dairy products with lactose at least once is similar

(A) On average, each child in Xantharu is not consuming more cow’s milk daily than each child in Tripania.
-> The assumption is not based on average consumption.

(B) Children in Xantharu are not more likely to consume lactose-free milk alternatives than are children in Tripania.
-> They may not consume any dairy or dairy substitute, also this makes no mention of the population as a whole.

(C) In Xantharu, only 20% of adults and teens experience severe lactose intolerance, compared to 40% of adults and teens in Tripania who experience severe lactose intolerance.
-> This seems to help justify the argument the best so far.

(D) The population size of Xantharu is comparable to the population size of Tripania.
-> We are using percentages, so the population size is irrelevant

(E) The rate of severe lactose intolerance among children in Xantharu has been lower than the rate in Tripania for over three generations.
-> It could be that adults in Tripania stop being lactose intolerant.
-> It could be that children in Xantharu with lactose intolerant parents do not let them consume lactose
-> It could be that a part of the Xantharu population has consistently not consumed lactose for over 3 generations.

Between C and E I will go with  C , given that the argument is talking about the population as a whole and C does a better job at defending this than E.

tkorzhan1995 · Answer

In the country of Xantharu, only 10% of children have experienced lactose intolerance episodes that were severe enough to require medical attention. However, in the neighboring country of Tripania, 30% of children have never experienced lactose intolerance episodes that required medical attention. Therefore, the inhabitants of Xantharu must be better adapted to digest lactose, found in dairy products commonly consumed by children, such as cow’s milk, than are the inhabitants of Tripania.

Which of the following is an assumption on which the argument depends?

(A) On average, each child in Xantharu is not consuming more cow’s milk daily than each child in Tripania.

(B) Children in Xantharu are not more likely to consume lactose-free milk alternatives than are children in Tripania.

(C) In Xantharu, only 20% of adults and teens experience severe lactose intolerance, compared to 40% of adults and teens in Tripania who experience severe lactose intolerance.

(D) The population size of Xantharu is comparable to the population size of Tripania.

(E) The rate of severe lactose intolerance among children in Xantharu has been lower than the rate in Tripania for over three generations.

Assessment:
X-S(10%) and NS(90%)
Y-S(70%) NS(30%)

Conclusion: The inhabitants of X are better adapted to lactose intolerance than inhabitants of Y. 
% of people who experience symptoms are used as an evidence for lactose intolerance. 
A-not correct
amount of milk consumed does not determine whether people are lactose intolerant. 
 B-selected
If people choose to select lactose free milk in X, they may not experience symptoms. Hence, % of people who experience severe symptoms will be lower. Conclusion that people in X are better adopted to lactose free milk will not be valid.  
C-Incorrect
It does provide similar information we know from the argument that higher % of people in Y experiences severe symptoms compared to X.
D-not correct
It does help us strenghthen the conclusion that number of people who experience severe symptoms is higher in Y than in X. However, it does not provide the linkage between # of people who experience symptoms and whether people are better equipped to deal with lactose intolerance. 
E-not correct
It does provide the same information as it was stated in the argument. Does not establish the linkage between # of people who experience severe symptoms and whether they are better equipped to deal with allergies.

behlmanmeet · Answer

In the country of Xantharu, only 10% of children have experienced lactose intolerance episodes that were severe enough to require medical attention. However, in the neighboring country of Tripania, 30% of children have never experienced lactose intolerance episodes that required medical attention. Therefore, the inhabitants of Xantharu must be better adapted to digest lactose, found in dairy products commonly consumed by children, such as cow’s milk, than are the inhabitants of Tripania.

Which of the following is an assumption on which the argument depends?

Solution: 
 Let children in Xantharu be 100X and in Tripania be 100T
children who have experienced lactose intolerance episodes that were severe enough to require medical attention in Xantharu= 10% of 100X= 10X
children who have not experienced lactose intolerance episodes that were severe enough to require medical attention in Xantharu= 90% of 100X= 90X
children who have not experienced lactose intolerance episodes that were severe enough to require medical attention in Xantharu= 70% of 100T= 70T
children who have experienced lactose intolerance episodes that were severe enough to require medical attention in Tripania= 30% of 100T= 30T
 
 The interesting thing to notice here is that in the conclusion the author mentions inhabitants and not only children but then he talks about efficiency or who's better at digesting lactose(found in dairy products commonly consumed by children). So, the author is basing it on children-consumed products which leads us to believe the comparison is based on children. I'm not 100% sure on this one but found this conclusion a bit confusing. Anyways let's move to the answers.
 
(A) On average, each child in Xantharu is not consuming more cow’s milk daily than each child in Tripania.:  The negation of this should destroy our conclusion but if On average, each child in Xantharu is consuming more cow’s milk daily than each child in Tripania then it strengthens the conclusion. Not our answer.

(B) Children in Xantharu are not more likely to consume lactose-free milk alternatives than are children in Tripania.:  Now, this is important. Remember the premise, only 10% have severe lactose intolerance requiring medical attention in Xantharu but 70% in Tripania. The author uses that to come to a conclusion. But if more children in Xantharu are using lactose-free milk then no wonder their percentages are low. It means it's not that is more adept at digesting lactose.

(C) In Xantharu, only 20% of adults and teens experience severe lactose intolerance, compared to 40% of adults and teens in Tripania who experience severe lactose intolerance.:  This is a bit tricky because if the conclusion has more emphasis on inhabitants and not children, this could work in our favor but then again its negation does not destroy our conclusion and it does not have to be necessarily true for our conclusion to hold. Even if the %ges were the same for both countries, we could make our case using the childrens' %ges.

(D) The population size of Xantharu is comparable to the population size of Tripania.:  Population does not matter because we are dealing with %ges of population. Even if Xantharu's population was quite smaller compared to Tripania. The fact that only 10% in Xantharu suffer from severe lactose intolerance requiring medical attention compared to 70% in tripania could very well be used to make our conclusion.

(E) The rate of severe lactose intolerance among children in Xantharu has been lower than the rate in Tripania for over three generations.:  rate does not matter and what up with past three generations what if before past 3 gens Tripania had lower rate.

Thus, answer is B.

JulienC · Answer

This was a great question for me as I've learnt a lot from the mistakes I made.
I still have some questions, however. like some clarification on one aspect of the question. 
To preface, I haven't started studying verbal yet, so I appologise if the answers are obvious.

-Is the argument the entire paragraph that the author writes, or is it just the claim the author makes after citing his/her facts/opinions?

To me, the argument would be "Therefore, the inhabitants of Xantharu must be better adapted to digest lactose, found in dairy products commonly consumed by children, such as cow’s milk, than are the inhabitants of Tripania." but maybe I'm wrong.

-Does the assumption have to be linked to the body of the text, the 'closing remarks' (what I would call the argument, see above), or both?

-Can there only ever be one assumption in an assumption question, or should you pick the best assumption?

-For those who are very experienced in answering these questions: Is it always better to create your own assumptions before going through the ones in the text?

I feel that I spent a lot of time thinking of the assumptions and paying attention to core of the argument, when I could have easily eliminated options C and E (the ones I thought were most likely) based on the level of specificity given.

Thank you for your time.

gmatophobia · Answer

Hello !

I can help answer few of your queries -

-Is the argument the entire paragraph that the author writes, or is it just the claim the author makes after citing his/her facts/opinions?

The argument consists of premise (facts, third party opinions etc.) and conclusion. In questions such as this, the conclusion plays an important role. All other details presented in the argument are just to relate to the conclusion.

Can there only ever be one assumption in an assumption question, or should you pick the best assumption?

From an answer point of view, there would always be one answer, other responses may seem tempting, however they would be incorrect on solid grounds of reasoning.

-For those who are very experienced in answering these questions: Is it always better to create your own assumptions before going through the ones in the text?

Definitely! The process is known as pre-thinking. Pre-thinking helps a lot and leads to quick answer choice elimination. Having said that, one can perform correct pre-thinking only when one has understood the passage.

Let me know if you have any more questions !

ElninoEffect · Answer

To start with there is no such thing as silly questions, it's silly not to ask one.! -Is the argument the entire paragraph that the author writes, or is it just the claim the author makes after citing his/her facts/opinions? The argument as the word suggests means disagreement, it can be between author and other person or a claim and a finding. Basically a disagreement over something. To me, the argument would be "Therefore, the inhabitants of Xantharu must be better adapted to digest lactose, found in dairy products commonly consumed by children, such as cow’s milk, than are the inhabitants of Tripania." but maybe I'm wrong. It's the conclusion . The conclusion means the final output or zest of the passage, the summary. There are certain markers for the same as to how to find out what is the conclusion if you are not able to figure out what is the conclusion. It generally starts with, therefore, hence, to conclude, etc. Note there can be more than one conclusion also.(not to make it complex but just letting you know) -Does the assumption have to be linked to the body of the text, the 'closing remarks' (what I would call the argument, see above), or both? Now coming to the assumption. What is an assumption.? Let's take an example. A picnic was organized for all the 12th graders of a school.(Premise) So john won't be going.(Conclusion) It means what all things.? Either john is not in 12th grade. (because it is only organized for 12th graders) or John is not in school. or John is a 12 grader but not in that school. Makes sense right.? So the assumption is an unstated statement for the conclusion to hold true. -Can there only ever be one assumption in an assumption question, or should you pick the best assumption? As I just gave an example, there can be multiple assumptions for a given statement but the options will be having only one assumption. You will never find options where multiple assumptions will be present and you have to select the best. -For those who are very experienced in answering these questions: Is it always better to create your own assumptions before going through the ones in the text? I am not experienced but let's say I have developed a taste for the same, so will answer your question. Yes, it's better to at least create one assumption before even reading the answer choice helps you focus on what you are looking for but again, as I said there can be multiple assumptions for a statement what assumption you thought might not be present but you will get a taste of it after a while.(thinking along the lines of question setter) I feel that I spent a lot of time thinking of the assumptions and paying attention to core of the argument, when I could have easily eliminated options C and E (the ones I thought were most likely) based on the level of specificity given. Learning new things always takes time as all the things in this world, what matters is the system should work every time and with better accuracy. So what matters is finding a system first. Learn to dissect the statement into the premise and the conclusion first.(finding the conclusion most important) but since you have just started there are plenty of resources that will teach you just the same. I hope I was of some assistance to you.! Rest Gmatclub is always rocking so don't bother knocking.!

Bp36mafia · Answer

Hi everyone , 
can someone help me to correct my approach for determining why option B is a correct option and why option D is not: 
conclusion : X's inhabitants are better suited to digest lactose as compared to T's inhabitants, given mostly children consume lactose products such as cow's milk.
pre thinking : given 10 % of children required medical support in X compared to 30 % of children in T. now one way to solve this question would be to check for an option which actually states that both countries have comparable population of children ( Why so because even if the conclusion is given about inhabitants , the major consumer of lactose based products are children. )
This does look similar to what option D is explaining but if we look closely it is actually giving the population comparison of overall population and not only of children. Therefore in my opinon a few repliues stating that the actual number wont matter , that is completely wrong , because actual number always do give an actual representation of the reality , where as percentage formula states : A = x% of B , x is representation . 
Now coming on to option B if an alternative option of milk is more readily available to children (which is the major demography on which conclusion is also drawn) and the likely hood is also high for consumption of these products then only the study would stand true.

gmatophobia · Answer

Hey  Bp36mafia

I think there are an issue with D -

The premise states information / provides factual information regarding the children in the two countries (Xantharu and Tripania). While the conclusion points to the entire population.

Conclusion:  Therefore,  the inhabitants of Xantharu  must be better adapted to digest lactose, found in dairy products commonly consumed by children, such as cow’s milk, than are the inhabitants of Tripania.

So essentially, we do not know about the lactose tolerance level of any other group apart from the children, however we are concluding based on a narrow dataset.

Even if we assume that the population of Xantharu is comparable to the population size of Tripania, so that the number is comparable, ambiguity still remains.

Option B is better suited as it brings in a new factor to consider - What if children in Xantharu are likely to consume alternatives, and thus they have not reported the lactose episodes.
Hence we cannot conclude inhabitants of Xantharu must be better adapted to digest lactose (they did not consume in the first place).

Hope this helps !

kkaryaa · Answer

It would not be D because the values are in percentages. the population is irrelevant because % provides an equal base

kkaryaa · Answer

the issue w D is percentages. 5 is 33.3% of 15 and 292677.5 is 33.3% 878677.

12 Days of Christmas GMAT Competition - Day 3: In the country of Xant

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12 Days of Christmas GMAT Competition - Day 3: In the country of Xant

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