word problem...quite tough .plz help

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A school administrator will assign each student in a group of n students to one of m classrooms. If 3 < m < 13 < n, is it possible to assign each of the n students to one of the m classrooms so that each classroom has the same number of students assigned to it?

(1) It is possible to assign each of 3n students to one of m classrooms so that each classroom has the same number of students assigned to it.

(2) It is possible to assign each of 13n students to one of m classrooms so that each classroom has the same number of students assigned to it.

Ans Is:- B
Source: — Data Sufficiency |

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by liferocks » Sat May 22, 2010 4:12 am
question is in simple term ,is n divisible by m where 3<n<13<n

From 1
3n=km..where k is any integer
so n=(k/3)m
no information on whether k/3 is integer.....insufficient

From 2
13n=km
Since m<13 and 13 is prime m is definitely not divisible by 13..so k is divisible by 13 or k/13 is integer
hence n/m=k/13=integer...n is divisible by m...sufficient

Ans option B
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by maqavi » Mon May 24, 2010 2:24 am
I need some expert advise on this:

Just like in this question, It says "is it possible to assign each of the n students to one of the m classrooms so that each classroom has the same number of students assigned to it? "

In which case I would assume, if I get one case that makes the statement right, then I m through. Do I have to look exhaustively all the time?

I would expect in that case the question should read as "Is it ALWAYS possible to assign each of the n students ........?"

How do I differentiate such cases and made a proper judgement?

Please help me logically understand the questions.