Life Expectancy

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Life Expectancy

by goelmohit2002 » Sat Sep 26, 2009 7:52 am
Hi All,

[spoiler]In the below question OG-12, Q1...OA = B. For kicking out C OG says that C strengthens the conclusion....

Can some one please tell how C strengthens the conclusion ? IMO C only tells for some XYZ reason average age is increased....but does not say anything about the perception of old age....which is the conclusion of the argument.
[/spoiler]
Kindly tell what I am missing here ?

========================================================
"Life expectancy" is the average age at death of the entire live-born population. In the middle of the nineteenth century, life expectancy in North America was 40 years, whereas now it is nearly 80 years. Thus, in those days people must have been considered old at an age that we now consider the prime of life.

Which of the following, if true, undermines the argument above ?
a) In the middle of the nineteenth century, the population of North America was significantly smaller than it is today.
b) Most of the gains in the life expectancy in the last 150 years have come from reductions in the number of infants who die in their first year of life.
c) Many of the people who live to an advanced age today do so only because of medical technology that was unknown in the nineteenth century.
d) the proportion of the people who die in their seventies is significantly smaller today than is the proportion of people who die in their eighties.
e) More people in the middle of the nineteenth century engaged regularly in vigorous physical activity than do so today.

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by goelmohit2002 » Sun Sep 27, 2009 1:08 am
Experts Kindly share your opinion please !!!!

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by vijay_venky » Sun Sep 27, 2009 3:44 am
I am not an expert but I think the following explanation might be useful

"Thus, in those days people must have been considered old at an age that we now consider the prime of life"

From this statement in the stimulus, there is a relation between the "old age" and the life expectancy that the author tries to cite.

I think the link is something like people at the age of life expectancy or above are considered to be old,
why?? because it is the average age at which people die.(age at death-->life expectancy-->old age)

And because the age at death is less earlier,"people must have been considered old at an age that we now consider the prime of life"

This relation is something that we need to attack. How could we attack this??

This is possible if we could prove that the life expectancy was low earlier because of reasons other than deaths at that particular age.

Option B does this.
Option C "Many of the people who live to an advanced age today do so only because of medical technology that was unknown in the nineteenth century. "

Option C says only because of med. tech.-->advanced age
means no med.tech. --> die at a smaller age
this strengthens the argument because it decreases the average age at which people die (it means age of death is decreased and so is the old age).

Hope this helps..,

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by goelmohit2002 » Sun Sep 27, 2009 3:57 am
vijay_venky wrote:I am not an expert but I think the following explanation might be useful

"Thus, in those days people must have been considered old at an age that we now consider the prime of life"

From this statement in the stimulus, there is a relation between the "old age" and the life expectancy that the author tries to cite.

I think the link is something like people at the age of life expectancy or above are considered to be old,
why?? because it is the average age at which people die.(age at death-->life expectancy-->old age)

And because the age at death is less earlier,"people must have been considered old at an age that we now consider the prime of life"

This relation is something that we need to attack. How could we attack this??

This is possible if we could prove that the life expectancy was low earlier because of reasons other than deaths at that particular age.

Option B does this.
Option C "Many of the people who live to an advanced age today do so only because of medical technology that was unknown in the nineteenth century. "

Option C says only because of med. tech.-->advanced age
means no med.tech. --> die at a smaller age
this strengthens the argument because it decreases the average age at which people die (it means age of death is decreased and so is the old age).

Hope this helps..,
Hi vijay_venky,

Thanks.

Basically what my doubt was that how does C strengthen the conclusion....yes IMO it strengthens that people have less average age earlier due to some XYZ reasons....(medical facilities not there may be one of them)....

so IMO it strengthens the premise(life expectancy was low earlier) not the conclusion that perception of old age was affected due to less medical care....

I hope I am clear in my doubt....basically what I mean to say is that if an option strengthens a premise then does it automatically strengthens the conclusion too ?

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by hector99 » Thu Sep 02, 2010 10:26 am
Hello Experts,

Could you please provide explanation for this question?

Thanks in advance!!!

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by beatthegmatinsept » Thu Sep 02, 2010 10:30 am
[spoiler]Is the OA B?[/spoiler] I only see that as an option that weakens the conclusion above.
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by hector99 » Thu Sep 02, 2010 10:34 am
Could you provide the explanation???
As I think that option B is also supporting the conclusion instead of weaking? :(

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by beatthegmatinsept » Thu Sep 02, 2010 10:41 am
"Life expectancy" is the average age at death of the entire live-born population. In the middle of the nineteenth century, life expectancy in North America was 40 years, whereas now it is nearly 80 years. Thus, in those days people must have been considered old at an age that we now consider the prime of life.

b) Most of the gains in the life expectancy in the last 150 years have come from reductions in the number of infants who die in their first year of life.

Conclusion: People in older times (middle of 19th century or 150ish yrs ago), must have been considered old at an earlier age (e.g. someone who was 40 yrs old was considered old 150 yrs ago, which is considered a prime age now).
B says, the average age at death has increased now because of lower infant death rates from 150 yrs ago. Thus, bringing the average age at death up in today's date.

Think of this as an Average/Mean problem in Quant, if a majority of elements in a set are 0, it brings the average down, when the 0 value elements are excluded, it brings the average up.

Does that help?
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by hector99 » Thu Sep 02, 2010 10:43 am
Hello Experts,

Could you please provide explanation for this question?

Thanks in advance!!!

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by pradeepkaushal9518 » Thu Sep 02, 2010 10:54 am
this is not so tough cr

average life in the middle of the nineteenth century was 40 years where as now it is 80 so people say at that time that age 40 is an old age. this has to be weaken

in the middle of nineteenth century take average of 2 persons one having age of 80 and other infant of life 2 yrs

so average is 82/2=41

now take two persons having life 80 and 70 average = 150/2=75

so gain in life expectancy in the last 150 yrs have come from reduction in the number of infants who die in their first year of life. not due to medical advancemet. medical advancement can increase life from 70 to 80 but not 2 yrs to 80 years
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by David@VeritasPrep » Thu Sep 02, 2010 11:27 am
I am not sure that you need an expert with the fine explanations from "pradeepkaushal9518" and from "beatthegmatinsept!"

This is from the OG 12th edition (page 526) and the official answer is B.

As mentioned in the explanations in the posts above, what you are looking for is another cause for the effect of the longer "life expectancy." The stimulus implies that the longer life expectancy is due to the fact that people in the 1850s uniformly died at an early age - around 40.

One very good way to weaken a question that involves cause and effect is to present another cause. Answer choice B offers the cause of lower infant mortality in recent years as the reason for the increased life expectancy.

The availability of an alternate cause weakens the proposed cause and so "b" is the answer.
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