Doubt

[nafishasan]

The average age of chairpersons in a large sample of departments at Delhi University is 55. The average age of chairpersons in those same departments 20 years ago was approximately ten years younger. On the basis of such data, it can be concluded that chairpersons in general tend to be older now. Which of the following casts the most doubt on the conclusion drawn above?

a) The dates when the chairpersons assumed their current positions have not been specified.
b) No information is given concerning the average number of years that chairpersons remain in office.
c) The information is based only on departments that have been operating for at least 20 years.
d) Only approximate information is given concerning the average age of the chairperson's 20 years ago.
e) Information concerning the exact number of departments in the sample has not been given.

[boazkhan]

IMO A. What is the source of this question?

[VivianKerr]

Conclusion: Chairpersons in general are older.

Evidence: Avg. age at Delhi is 55, was 45 twenty years ago.

Assumption: The trend at Delhi Univ. is true for all chairpersons.

Question: What WEAKENS?

Prediction: If the trend is NOT true, accurate or applicable.

A - could weaken
B - could weaken
C - this strengthens since it makes the trend more accurate
D - irrelevant -- argument already states "approximately"
E - irrelevant -- the number of depts is not the concern

It's down to A and B. So, how are they different? A focuses on the date when they assumed, or started, their positions. B focuses on the lack of knowing how long the chairpersons have bee there. B would give us the most info to strengthen the argument, so my choice is B. Difficult question!

[santhoshsram]

Hi Vivian,
Could you please explain how C strengthens the argument. I thought it weakens the argument. Here is my reasoning.

The premises are about chairpersons from the sample set, but the conclusion is about chairpersons in general - I thought this was a slight shift.

C says that the information (I took information to mean the premises) is based only on departments that were operating for 20 years. So this trend pertains only to the sample set. For example outside of the sample set 20 years ago there could have been many departments (which are no longer in existence) whose chairpersons were older than 55 yrs on average. Or today there can be more departments, outside the sample set, whose chairpersons are 45 years or younger on average.

Since C restricts the trend only to the sample set, the conclusion which generalizes the observation from the sample set would be weakened right?

Please let me if I'm overlooking something.

[[email protected]]

In my opinion, C.

Reason: The information is based ONLY ON departments that have been operating for at least 20 years. But conclusion says that chairpersons in general tend to be older NOW. So to weaken the conclusion, we can say that there are many departments which are not older than 20 years (i.e outside the sample set) having average age of chairpersons lesser than 55. So what i want to say is author assumes that what is true for departments older than 20 yrs is true for all departments.

Please correct me if I am wrong.

[money9111]

IMO B - I just wanted to come on here and see if I could still remember these things! (I'm bored atm)

[[email protected]]

nafishasan: Whats the OA ?

[justharsha]

OA Please?

I think its C

[[email protected]]

After the POE analysis, the answer that strikes me is the option B. nothing else.

I do not know why...

Well according to me, this question is more like an evaluate question. Which is that one option that can actually, evaluate the conclusion above or break the argument completely.

that option is a definite B.

If let us say that one of the persons, stayed or held the office for more than 20 years so the conclusion shall be strengthened with 100% conviction.

Let us say that the maximum number of persons that held the office for maximum number of years, is let us say 2 or 5, then the question directly goes on to what is the age of election now i.e after 20 years. So this option raises some concern on the validity of the argument.

This is the only of the all that can weaken the argument according to me...

[dhonu121]

I feel the right option is C.
While the stimulus presents premise about departments that were 20 years earlier and that are now, it claims something about chairpersons in general.
What if, only a few of the departments have been surveyed(i.e just a few departments were their 20 years earlier which are present now), then this data is not representative of the entire organisation. Hence, the claim about chairpersons in general can be wrong.
C just says that.

I'll go with C.

[vk_vinayak]

Had narrowed down my potions to B and C. I will go with B.

B says that we dont know about the average tenure of chair persons. May be all the oldest ones are made chairperson in the last two years. And before that it could have been 50. This option is more vulnerable.

While C says that only 20 years of data in considered. If the data is true is sufficient to say that average age of chairperson is more than what it was 20 years ago.

[hultt]

confused between B and C..

any more detailed explanations between B and C??

[quiimari]

Conclusion: Chairpersons in general are older.

Evidence: Avg. age at Delhi is 55, was 45 twenty years ago.

Assumption: The trend at Delhi Univ. is true for all chairpersons.

Question: What WEAKENS?

Prediction: If the trend is NOT true, accurate or applicable.

A - could weaken
B - could weaken
C - this strengthens since it makes the trend more accurate
D - irrelevant -- argument already states "approximately"
E - irrelevant -- the number of depts is not the concern

It's down to A and B. So, how are they different? A focuses on the date when they assumed, or started, their positions. B focuses on the lack of knowing how long the chairpersons have bee there. B would give us the most info to strengthen the argument, so my choice is B. Difficult question!

Horrible explanation. It doesn't matter if the CEOs are the same - they have still gotten older. OA is C because of the scope shift mentioned by santhoshsram. Here is a structurally identical question
https://gmatclub.com/forum/the-average-a ... fl=similar