After you answer the above question, here comes a related

来源: bearsback 于 2009-12-06 19:07:30 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (162 bytes)
本帖于 2009-12-10 08:06:15 时间, 由版主 林贝卡 编辑

one:
each of the 100 people visits this forum with prob. 0.5. What is the standard deviation for the total number of times these people visit the forum?
ha

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• 我也想搞清楚：什么是standard deviation? 我的书上都 -not.me- ♀ 给 not.me 发送悄悄话 not.me 的博客首页 (54 bytes) () 12/06/2009 postreply 19:23:48

• standard deviation 很难。我一直没搞懂。 -bearsback- ♂ 给 bearsback 发送悄悄话 bearsback 的博客首页 (69 bytes) () 12/06/2009 postreply 20:16:32

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