Critical Reasoning

The average age of chief executive officers (CEO's) in a large sample of companies is 57. The average age of CEO's in those same companies 20 years ago was approximately eight years younger. On the basis of those data, it can be concluded that CEO's 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 CEO's assumed their current positions have not been specified.
(B) No information is given concerning the average number of years that CEO's remain in office.
(C) The information is based only on companies that have been operating for at least 20 years.
(D) Only approximate information is given concerning the average age of the CEO's 20 years ago.
(E) Information concerning the exact number of companies in the sample has not been given.


OA ...

Premise :
The average age of chief executive officers (CEO's) in a large sample of companies is 57. The average age of CEO's in those same companies 20 years ago was approximately eight years younger.

Conclusion:
On the basis of those data, it can be concluded that CEO's in general tend to be older now.

IMO : B

C,D,E are clearly out.
We are talking about the age.A discusses the date of joining.Hence out.

B) No information is given concerning the average number of years that CEO's remain in office.
Correct. If these CEOs have been working in these companies for eight years then the conclusion is not valid.
It is possible that the CEOs have been working in these companies for eight years or more and they were comparatively younger when they joined.

Please post OA along with the source
Please post source along with the OA.

Only not so nonsensical choice seems to be B. If avg no of year CEO's work is 10 year, it is likely most of them will change soon possibly changing demography, but if it is a year or less, then it make sense new people coming are older in age.

Source is 1000CR . Will post the OA in some time , need some more insights into the question . This one is tricky , i was completely lost at this one . You might want to reconsider attempting this question .

The average age of chief executive officers (CEO's) in a large sample of companies is 57. The average age of CEO's in those same companies 20 years ago was approximately eight years younger. On the basis of those data, it can be concluded that CEO's 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 CEO's assumed their current positions have not been specified.
(B) No information is given concerning the average number of years that CEO's remain in office.
(C) The information is based only on companies that have been operating for at least 20 years.
(D) Only approximate information is given concerning the average age of the CEO's 20 years ago.
(E) Information concerning the exact number of companies in the sample has not been given.


I was stuck between B & C, and I think I would go with C. Please tell me if my reasoning is correct.

C says that only information about companies that have been operating for twenty years has been given. So, these might be huge firms which might have grown in the last 20 years, and with it the age and experience of the CEO would have gone up.

But for us to conclude that the average age in general has gone up, we need to prove it for all companies.
What if new young companies have come up with younger CEO's. So, since it would not be true in general, C offers us a choice that I believe casts a doubt on the conclusion.

I'm going with C. B is the one tricking me to choose between the two. Please provide explanation. Thank you!

This seems very hard.

1. Average age of CEOs in a large sample is 57
2. 20 Years ago the age of that same sample was 49
3. All CEOs are older now.

A. Incorrect. What dates the CEOs took office is irrelevant. We are concerned with the age of the CEOs not how many years they have been in office.

B. Incorrect. Again this is something similar to A. It is trying to distinguish between age and years in charge.

C. Correct. The argument is tying in companies that are 20 years old with all companies. Though the same is large that does not mean there is a larger sample of other companies that have young CEOs that were never candidates for this survey

D. Incorrect. We know they were 49 then and 57 now. No matter how much more accurate that number is would not change the fact that they are older now.

E. Incorrect. Knowing the number in the sample by itself is not going to cast significant doubt on the results. Sample size vs population is important but not sample alone.

E.

IMO C

What's the OA ?

IMO B as well.

AIM GMAT wrote:The average age of chief executive officers (CEO's) in a large sample of companies is 57. The average age of CEO's in those same companies 20 years ago was approximately eight years younger. On the basis of those data, it can be concluded that CEO's 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 CEO's assumed their current positions have not been specified.
(B) No information is given concerning the average number of years that CEO's remain in office.
(C) The information is based only on companies that have been operating for at least 20 years.
(D) Only approximate information is given concerning the average age of the CEO's 20 years ago.
(E) Information concerning the exact number of companies in the sample has not been given.


OA ...

Thanks guys for wonderful explanations , special thanks goes to akash.delsaria and fitzgerald23 !!

OA is C.

Thank you fitzgerald23 for your extensive response!