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OG 12- DS128

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OG 12- DS128

by Mom4MBA » Sun Jul 10, 2011 9:35 pm
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.

My question here is that shouldn't "each student in a group of n students" be "each student from a group of n students", this would have made the question more clear in meaning?
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by kevincanspain » Sun Jul 10, 2011 10:46 pm
Mom4MBA wrote:
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.
What do you say?

What group are you in? or What group are you from?


My question here is that shouldn't "each student in a group of n students" be "each student from a group of n students", this would have made the question more clear in meaning?
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by krnverma » Tue Jul 12, 2011 11:21 pm
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.

Hi everyone,
I am using this post as, even, I have a doubt about the Q128.

I could easily understand how statement (1) is not sufficient, however, I have a doubt. The OG explained that if we can show an example which proves that 3n is divisible by m and n alone is not then we can say that the statement is not sufficient.

As for statement (2), after reading the explanation in the OG I felt that the solution there might not strike me intuitively under exam pressure. I preferred the solution explained by the Grockit OG TV, they simply explained that if 13n is divisible by m then m has to be a factor of 13n (as we know m cannot be a factor of 13, subsequently, it is pretty easy to see that n has to be divisible by m.)

Ideally, this should be it and I can move forward to reviewing the next question, but I am not convinced. What if I apply the same logic to statement (1)? That is, if 3n is divisible by m then as we know m cannot be 3 and, also as 3 is a prime number, n should be divisible by m but IT IS NOT.

Could some one throw some light and make things clearer?

Thanks in advance.

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by beatthegmat.garry » Sun Jul 17, 2011 11:25 am
Quote: if 3n is divisible by m then as we know m cannot be 3 and, also as 3 is a prime number, n should be divisible by m but IT IS NOT.

In the expression 3n/m; '3' can be consumed by m (m=6 ie; 2*3) as m is greater than 3 (m=6,9 12).
But in the expression 13n/m; '13' cannot be consumed by m since m is less than 13.
Hence 3n/m may not indicate that n/m gives an integer for all instance. But 13n/m does indicate that n/m gives an integer.

Hope this helps! :)
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