OG13 DS 135 求大牛解答 答案讲解看不懂 （选b）

freegg

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 student to one of the m classrooms so that each classroom has the same number of students assigned to it?) it is possible to assign each of 3n students to one of m classroom so that each classroom has the same number of student 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 i

oliverw

Thx!

bici

从别的贴看到的，觉得解答的很好
OG13--135 DC
我理解的这个题目的意思是说，n个学生分配到m个教室，如果每个教室人数相同，设n/m=A,则A肯定为整数。
选项1,3n/m为整数，因为3<m<13<n，假如m=6,n=14,则n/m不为整数；假如m=6,n=18,n/m为整数。
所以选项1不充分

选项2，13n/m为整数，3<m<13<n，m不可能含有13这个因子，所以可以得出n/m一定为整数；选项2充分