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are all the numbers of certain list of 15 numbers equal?

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by Taniuca » Sun Aug 21, 2011 10:58 am
Are all the numbers of a certain list of 15 numbers equal?
1) the sum of all the numbers in the list is 60.
2)the sum of any 3 numbers in the list is 12.

How can this problem solved in an easier way than the one offered at the Official guide problem-133?
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by GMATGuruNY » Sun Aug 21, 2011 12:16 pm
I posted an explanation here:

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by GmatKiss » Mon Aug 22, 2011 2:17 am
Taniuca wrote:Are all the numbers of a certain list of 15 numbers equal?
1) the sum of all the numbers in the list is 60.
2)the sum of any 3 numbers in the list is 12.

How can this problem solved in an easier way than the one offered at the Official guide problem-133?
from given, we have an instinct that all the numbers has to be 4, while few numbers can be around it

from 1)
the set can have any numbers, not necessarily 4

from 2)
All the numbers in the set has to be 4.
Imagine we have a number 1 or 3, then, if this number(1 or 3) is added with 4,4, we will not end up with 12!!

IMO: B

Without analysis, C seemed to be the answer!!
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