中学数学问题，请帮忙

1. A committee of 3 teachers are to select the winner from among ten students nominated for special award. The teachers each make a list of their top three choices in order, the lists have only one name in common, and that name has a different rank on each list. in how many ways could the teachers have made their list?
2. In how many ways could a class of 18 students divide into groups of 3 students?
Urgent

Thanks in advance

所有跟帖： 

• 回复：中学数学问题，请帮忙 -ziseyanzi- ♂ (76 bytes) () 02/18/2007 postreply 23:43:20

• 到脑筋急转坛也去发个帖吧，他们那边的数学家们都闲得发慌了。 -太平洋- ♂ (0 bytes) () 02/19/2007 postreply 06:31:35

• P(3) × C(10, 3); C(18, 3) -ppzcgg- ♀ (5 bytes) () 02/19/2007 postreply 09:08:18

• thanks -donz94086- ♂ (0 bytes) () 02/19/2007 postreply 20:00:18

• haha, misread one info. The revised answer --> -ppzcgg- ♀ (520 bytes) () 02/21/2007 postreply 10:50:31

• 2) C(18, 3) × C(15, 3) × C(12, 3) × C(9, 3) × C(6, 3) × C(3 -ppzcgg- ♀ (82 bytes) () 02/21/2007 postreply 11:45:40

• P（3）*C（3，10）*C（1，3）*C（2，7）*C（2，5） -中国民航- ♂ (419 bytes) () 02/20/2007 postreply 21:56:36