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advice need

by likewhoa » Wed Nov 21, 2007 3:59 pm
Among the list of 10 numbers, 4,6,8,10,12,14,16,18,20,22, a new list (List M) 8 numbers can be made after taking out 2 numbers. What is the standard deviation of this new list (List M) of 8 numbers?

(1) The standard deviation of "List M" and the previous list (of 10 numbers) is the same

(2) List M does not include the number 22.


Can anyone help solving this problem?
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Source: — Data Sufficiency |
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by camitava » Wed Nov 21, 2007 9:16 pm
likewhoa, IMO A. From B, according to me it will be tough to find out the other number that has been taken out from the list of 10 numbers.
Correct me If I am wrong


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Amitava
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by sujaysolanki » Thu Nov 22, 2007 2:14 am
Whats the appoach to these kind of problems ...

Do we pick numbers ..thats wud be tedious

Is there a shorter way ?

All we know id SD/10 = SD/8 ...and we can find the SD
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by camitava » Thu Nov 22, 2007 7:31 am
sujaysolanki, look from the question, statement - 1 is coming very sure to be he best option to chose. But stmt-2, after having little calculation, stmt-2 will come to you as not the correct option to chose. Thats how I chose the answer without doing any calculation obviously.
Correct me If I am wrong


Regards,

Amitava
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by sujaysolanki » Thu Nov 22, 2007 7:36 am
ya makes sense ..thnks
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