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# V21-41

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Manager
Joined: 19 May 2015
Posts: 129

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16 Feb 2018, 14:37
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45% (medium)

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77% (01:19) correct 23% (01:07) wrong based on 13 sessions

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In the nation of Pelmenia, 20% of 18-year-olds are left-handed, while just 10% of 45-year-olds and 2% of 70-year-olds are left-handed. But the percentage of children born left-handed has never changed in Pelmenia, nor have societal attitudes toward left-handedness.

Which of the following, if true, most helps to explain the variation in left-handedness among Pelmenians?

A. The number of children born each year in Pelmenia has steadily increased over the past seventy years.
B. In Pelmenia, left-handers are no more likely to perish in accidents than right-handers.
C. In Pelmenia, ambidexterity is not considered a desirable attribute.
D. In Pelmenia, women have a significantly lower life expectancy than men, and women are also more likely to be born left-handed.
E. As Pelmenians age, they become less likely to participate in surveys regarding handedness or hand dominance.
Manager
Joined: 19 May 2015
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16 Feb 2018, 14:38
Official Solution:

In the nation of Pelmenia, 20% of 18-year-olds are left-handed, while just 10% of 45-year-olds and 2% of 70-year-olds are left-handed. But the percentage of children born left-handed has never changed in Pelmenia, nor have societal attitudes toward left-handedness.

Which of the following, if true, most helps to explain the variation in left-handedness among Pelmenians?

A. The number of children born each year in Pelmenia has steadily increased over the past seventy years.
B. In Pelmenia, left-handers are no more likely to perish in accidents than right-handers.
C. In Pelmenia, ambidexterity is not considered a desirable attribute.
D. In Pelmenia, women have a significantly lower life expectancy than men, and women are also more likely to be born left-handed.
E. As Pelmenians age, they become less likely to participate in surveys regarding handedness or hand dominance.

We are asked to select an answer choice that, if true, most helps to explain the variation in left-handedness among Pelmenians. Before we analyze the answer choices, let's make sure we have a clear understanding of the variation that we need to explain

"In the nation of Pelmenia, 20% of 18-year-olds are left-handed, while just 10% of 45-year-olds and 2% of 70-year-olds are left-handed." - So the percentage of Pelmenians who are left-handed seems to vary with age. Of course, it is certainly possible that the percentage fluctuates in between the three given ages, but, based on the data given in the passage, it seems as though the percentage goes down as age goes up

"The percentage of children born left-handed has never changed in Pelmenia." - One possible explanation for the variation is that the percentage of Pelmenian children born left-handed has steadily increased over the course of the past 70 years. This statement eliminates that possibility, so we need another explanation

"Societal attitudes toward left-handedness" have never changed in Pelmenia. - Another possible explanation for the variation is that societal attitudes toward left-handedness have changed over the course of the past 70 years. For example, 70 years ago, left-handed Pelmenian children may have been viewed unfavorably and thus may have been treated in ways that decreased their odds of leading healthy and successful lives. But the information given in the passage eliminates this possible explanation

So we need to explain why the percentage of Pelmenians who are left-handed seems to decrease with age, despite no change in the percentage of children who are born left-handed or in attitudes toward left-handedness

(A) The number of children born each year in Pelmenia has steadily increased over the past seventy years

We are trying to explain a variation in the PERCENTAGE of Pelmenians who are left-handed. If the number of children born each year has steadily increased, we would still expect the PERCENTAGE of left-handed children to remain the same each year. Thus, we still need something to explain why the percentage of Pelmenians who are left-handed decreases as age increases. Choice (A) does not explain the variation and can be eliminated

(B) In Pelmenia, left-handers are no more likely to perish in accidents than right-handers

A possible explanation for the variation is that left-handers ARE more likely to perish in accidents than right-handers. This would explain why the percentage of Pelmenians who are left-handed decreases as age increases. However, choice (B) tells us that left-handers are NO more likely to perish in accidents than right-handers, eliminating this possible explanation. Thus, choice (B) does not explain the variation and can be eliminated

(C) In Pelmenia, ambidexterity is not considered a desirable attribute

Choice (C) addresses another possible explanation for the variation. If ambidexterity WERE considered a desirable attribute, perhaps many left-handed Pelmenians would gradually learn to become ambidextrous over the course of their lives. This could potentially lead to a gradual decrease with age in the percentage of Pelmenians who are considered left-handed (once they learn to use both hands equally well, they would be considered "ambidextrous" and not "left-handed"). Choice (C) eliminates this possible explanation and does not provide an alternative, so we can get rid of (C)

(D) In Pelmenia, women have a significantly lower life expectancy than men, and women are also more likely to be born left-handed

Now we are on to something. If women are more likely to be born left-handed, then we can assume that the majority of left-handed Pelmenian children are female. If women and men had the same life-expectancy, we would expect the percentage of Pelmenians who are left-handed to remain the same as age increases. However, if women were more likely to die at a younger age, we would expect the percentage of Pelmenians who are left-handed to DECREASE as age increases

In other words, if you are left-handed, you are probably a woman. Women, on average, die younger than men. Thus, on average, right-handers are likely to live longer than left-handers. This would explain the variation described in the passage, so hang on to (D)

(E) As Pelmenians age, they become less likely to participate in surveys regarding handedness or hand dominance

If choice (E) said that LEFT-HANDED Pelmenians become less likely to participate in such surveys as they age, then we would have a possible explanation for the variation described in the passage. However, as written, choice (E) does not explain why the percentage decreases with age. Even if a smaller portion of Pelmenians respond to such surveys as they age, we would still expect the ratio of left-handers to right-handers to remain about the same. Choice (E) does not explain the variation and can be eliminated

Choice (D) is the best answer.

Intern
Joined: 14 Aug 2017
Posts: 15
GMAT 1: 660 Q49 V34

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12 Oct 2018, 05:10
How is A wrong?
If population is increasing every year then total born increases . Percentage of left handed remains same but since population is increasing,5% of 100 will be greater than 5% of 200 and hence explains decrease.

Let me know where i went wrong
Intern
Joined: 13 Dec 2018
Posts: 7

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20 Apr 2019, 12:36
Why is option A wrong.

20% of 100 is less than 20% of 1000. SO if population increases and % remains same, this explains the increasing left hand-ers each year and hence the decrease in their % as the age graph increases.
Re: V21-41   [#permalink] 20 Apr 2019, 12:36
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# V21-41

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