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6983manish: Senior | Next Rank: 100 Posts; Posts: 65; Joined: Mon Mar 07, 2011 12:27 am; Thanked: 6 times

by 6983manish » Mon Mar 28, 2011 1:32 am

The average age of chief executive officers 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 avg no 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 avg age of the CEO's 20 years ago.
(E) Information concerning the exact number of companies in the sample has not been given.

Source: Beat The GMAT — Critical Reasoning | Mon Mar 28, 2011 1:32 am

Rezinka: Master | Next Rank: 500 Posts; Posts: 131; Joined: Fri Oct 15, 2010 2:39 am; Location: New Delhi, India; Thanked: 11 times

by Rezinka » Mon Mar 28, 2011 4:05 am

IMO :B

fitzgerald23: Master | Next Rank: 500 Posts; Posts: 219; Joined: Mon Mar 08, 2010 8:51 pmFollowed by: 5 members; Thanked: 62 times; GMAT Score:750

by fitzgerald23 » Mon Mar 28, 2011 8:17 am

1. CEOs in a group of companies are now 57
2. 20 years ago CEOs in that same group were only 49
3. All CEOS are older now than they were 20 years ago

When you write it out like that its very clear what the answer will likely be. The author is making the assumption that this group of companies is representative of the whole business world.

A. Incorrect. The question is concerned with age, not time as an officer

B. Incorrect. How long they remain in office makes no difference

C. Correct. To be included in this sample the company had to be around for 20 years. Imagine there were 100 companies in that sample. In that time 1000 companies have come into existence and their CEOs average 40 years of age. Now the average age of the whole population is going to be way younger than 49, making the conclusion incorrect.

D. Incorrect. Its pretty exact and unimportant anyway.

E. Incorrect. The number in the sample isnt that important. You need the sample relative to the population to be important.

Target2009: Legendary Member; Posts: 574; Joined: Sat Oct 31, 2009 1:47 pmFollowed by: 5 members; Location: USA; Thanked: 29 times

by Target2009 » Mon Mar 28, 2011 5:56 pm

+1 to C

Regards
Abhishek
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