(1/2)^3*4=1/2?shoud be4* (1/2)^3*(1/2)=1/4,1-,,,=9/16

來源: jinjing 於 2010-08-02 06:52:24 [] [舊帖] [給我悄悄話] 閱讀數 : (258 bytes)
回答: 生活中的數學 ３（續） 由 NaCl 於 2010-08-01 08:16:56

Second time 0: P(E0)=C(4,0)*(2/3)^4*(1/3)^0=16/81
Second time 1: P(E1)=C(4,1)*(2/3)^3*(1/3)^1=32/81
The answer P(E)=[(16/81)*(9/16)+(32/81)*(7/8)]/[16/81+32/81]=37/48
Please check it.
Thank you,let me review Bernoulli formula and Prob. Tree.

所有跟帖： 

• 回複: you missed one point. -NaCl- ♂ 給 NaCl 發送悄悄話 (73 bytes) () 08/02/2010 postreply 12:50:42

• I didn't miss.how much get 0 or 1,in second? We -jinjing- ♀ 給 jinjing 發送悄悄話 (22 bytes) () 08/02/2010 postreply 13:25:05

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