求助一道数学题

gpc7109 · 发表于 2009-7-31 20:24:00

请ＮＮ人帮助解答．

A company has assigned a distinct 3-digit code number to each of its 330 employees . Each number is formed from the digit :2 ,3, 4, 5 ,6,7,8,9,

and no digit appears more than once in any one code number, How many unassigned code numbers are there ?

A . 6

B.58

C.174

D.182

E.399

ZH280113 · 发表于 2009-7-31 20:52:00

选A吗？

A(8,3)-330?

momokingdom · 发表于 2009-7-31 20:57:00

同楼上，C(8,3)A(3,3)-330 =6 选A

ellaellali · 发表于 2009-7-31 20:59:00

P3（8）-330 = 8×7×6-330=6，选A

gpc7109 · 发表于 2009-7-31 21:49:00

答案是A. 太感谢了.我想了很久

[此贴子已经被作者于2009/7/31 21:51:52编辑过]

所属分类: GMAT考试