OG12th DS 128

meckychen · 发表于 2010-1-18 10:18:50

A school administrator will assign each students 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.

The answer is B. Why?

Thank you.

aniec · 发表于 2010-1-18 10:37:01

题目说了半天，其实就是问，

3<m<13<n, n是否能整除m？条件1，3n能整除m；条件2，13n能整除m。

这就简单了，m的取值可以是2，3，4，5，6，7，8，9，10，11，12，这样，根据条件1，3n能整除m，无法判断出n是否能整除m，因为m有可能是6，9，或者12。但是条件2，13n可能整除m的话，并且m的取值中没有能整除13被13整除的，这就说明13n中的n一定正整除m。所以条件2可以判断

meckychen · 发表于 2010-1-18 13:41:30

thank you

zwhjzwhj · 发表于 2013-6-26 12:37:23

为什么我感觉OG解释的不对，

第一题OG说不sufficient，if m = n = 9和 if m = 9 and n = 12，但题目已经给出了If 3 < m < 13 < n。如果n大于13的话，所有3n可以整除m的，n都应该能整除m，也就是只有n=12是不符合这个条件的。。。

难道是我哪里理解错了么。

sdcar2010 · 发表于 2013-7-6 21:52:54

zwhjzwhj 发表于 2013-6-26 12:37
为什么我感觉OG解释的不对，

第一题OG说不sufficient，if m = n = 9和 if m = 9 and n = 12，但题目已经给 ...

Simple. Let m =9, n = 39. What is your analysis?

zwhjzwhj · 发表于 2013-7-8 11:40:55

sdcar2010 发表于 2013-7-6 21:52
Simple. Let m =9, n = 39. What is your analysis?

我不明白题目解释里的if m = n = 9和 if m = 9 and n = 12这两个是什么意思，题目不是已经给出了条件 3 < m < 13 < n 了吗？

OG12th DS 128

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