I'm happy to help.IMPORTANT NOTES:This question is about “sampling” like the technique used in statistic (Quant).
KEY point is: the sample used to generalize the whole set MUST be comprehensive enough.
ANALYZE THE STIMULUS:
Fact: The average age of chief executive officers (CEO’s) in a large sample of companies is 57.
Fact: The average age of CEO’s in those same companies 20 years ago was approximately eight years younger.
Conclusion: CEO’s in general tend to be older now.
Which of the following casts the most doubt on the conclusion drawn above?ANALYZE EACH ANSWER:
(A) The dates when the CEO’s assumed their current positions have not been specified.Wrong.
A may weaken or NOT. What if the CEO’s are appointed to their position at younger ages. Thus, A does not weaken the conclusion.
(B) No information is given concerning the average number of years that CEO’s remain in office.Wrong.
The average number of years in office DIFFERS from how old the CEO’s are when they are appointed to their positions.
(C) The information is based only on companies that have been operating for at least 20 years.Correct.
C weakens the conclusion by showing that the sample
used to GENERALIZE
the conclusion is not comprehensive.
The argument just uses information of companies operating for at least 20 years to make a conclusion for every CEO’s.
(D) Only approximate information is given concerning the average age of the CEO’s 20 years ago.Wrong.
The conclusion may be still correct if the information of the average age of the CEO’s 20 years ago is COMPRESHENSIVE enough. It means the sample can represent the whole set.
(E) Information concerning the exact number of companies in the sample has not been given.Wrong.
Out of scope. We do not need information about how many companies in the sample. There are 20, or 200. We don’t know. Thus, E does not help.
Hope it helps.
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