面试问题请教

刚从一个公司面试回来。有一问题没有做出，请教这里的高手：
有一块草地，牛来吃草。吃的rate是一样的。三只牛可以吃3天，两只牛吃6天，问一只牛可吃几天？注意：草是在长的！

另外：在找工作，有一天，一“中介”来电，问了经历，技术，背景，介绍了他有的位子，突然问“你的生日是那天”，当时警惕不高，犹豫中还是说了，以为是背景调查需要的。事后越想越不对。如果我怀疑他要盗用我的身份，怎样预防呢？该与谁联系？

谢谢诸位。

所有跟帖： 

• 好象一头牛永远也吃不完，不知道对不对 -撅着挺好- ♂ (0 bytes) () 05/03/2009 postreply 07:35:06

• 9天 -richard0920- ♀ (0 bytes) () 05/03/2009 postreply 18:50:16

• 回复：面试问题请教 -streetwalker- ♂ (319 bytes) () 05/03/2009 postreply 09:21:58

• It's not that simple. -rubikscube- ♀ (287 bytes) () 05/03/2009 postreply 13:28:07

• my assumption is that a fixed size of lawn always grows the same -streetwalker- ♂ (269 bytes) () 05/03/2009 postreply 14:58:25

• My assumption is that that grass can't grow anymore -Rubikscube- ♀ (94 bytes) () 05/03/2009 postreply 15:24:54

• Forever. The key is to figure out the growth rate -Rubikscube- ♀ (910 bytes) () 05/03/2009 postreply 09:49:04

• 可以直接跟他说，简历里都写了生日了， -xtd- ♀ (0 bytes) () 05/03/2009 postreply 10:13:03

• 简历里都写了生日了？？？？ -wxc369- ♂ (28 bytes) () 05/03/2009 postreply 10:31:06

• 我来说说。 -sigma- ♂ (110 bytes) () 05/03/2009 postreply 10:34:30

• 你面试什么工作？ -云河- ♀ (37 bytes) () 05/03/2009 postreply 11:03:17

• 或者是放高利贷的... -rubikscube- ♀ (213 bytes) () 05/03/2009 postreply 11:14:08

• IT. -WatchOnly- ♀ (0 bytes) () 05/03/2009 postreply 12:26:52

• Another way to look at this problem. -Rubikscube- ♀ (584 bytes) () 05/03/2009 postreply 12:49:01

• 这就是著名的牛顿吃草问题 -怪哉- ♂ (85 bytes) () 05/03/2009 postreply 13:22:36

• What' wrong with this? -0.0001- ♂ (285 bytes) () 05/03/2009 postreply 13:23:33

• 数字太高深,看不懂 -喜气连年- ♀ (0 bytes) () 05/03/2009 postreply 14:23:35

• Surprising, isn't it? What' wrong with this? -戏雨飞鹰- ♀ (0 bytes) () 05/03/2009 postreply 14:27:43

• 一头牛永远吃不完这块草！ -为了活着- ♂ (127 bytes) () 05/03/2009 postreply 17:12:06

• typical scenario in China--老牛吃嫩草，永远吃不完 -撅着挺好- ♂ (0 bytes) () 05/03/2009 postreply 14:34:31

• 呵呵,嫩草一茬又一茬,春风吹又生 -喜气连年- ♀ (0 bytes) () 05/03/2009 postreply 14:53:35

• exactly! -撅着挺好- ♂ (0 bytes) () 05/03/2009 postreply 15:01:40

• off the top of my head, the guy is so lucky, I'm kinda jealous,h -撅着挺好- ♂ (0 bytes) () 05/03/2009 postreply 18:37:58