conditional probability

天才A

諗左好耐都唔識..

已知b市 之天氣由上一天決定
假如 今天 下雨，明天下雨機會率為0.6
假如今天 不下雨，明天不下雨機會率為0.8

已知星期日 不下雨
求星期5下雨之機會率

應該係
P(星期五下雨丨星期日不下雨)
-------------------------------
    P(星期日不下雨)

分子易搞..
分母點搞??

-終場ソ使者-

Use tree diagram,
the required probability=(0.2)(0.6)(0.6)(0.6)(0.6)+(0.2)(0.6)(0.6)(0.4)(0.2)+(0.2)(0.6)(0.4)(0.2)(0.6)+(0.2)(0.6)(0.4)(0.8)(0.2)+(0.2)(0.4)(0.2)(0.6)(0.6)+(0.2)(0.4)(0.2)(0.4)(0.2)+(0.2)(0.4)(0.8)(0.2)(0.6)+(0.2)(0.4)(0.8)(0.8)(0.2)+(0.8)(0.2)(0.6)(0.6)(0.6)+(0.8)(0.2)(0.6)(0.4)(0.2)+(0.8)(0.2)(0.4)(0.2)(0.6)+(0.8)(0.2)(0.4)(0.8)(0.2)+(0.8)(0.8)(0.2)(0.6)(0.6)+(0.8)(0.8)(0.2)(0.4)(0.2)+(0.8)(0.8)(0.8)(0.2)(0.6)+(0.8)(0.8)(0.8)(0.8)(0.2)=0.32992

天才A

Use tree diagram,
the required probability=(0.2)(0.6)(0.6)(0.6)(0.6)+(0.2)(0.6)(0.6)(0.4)(0.2)+(0.2) ...
-終場ソ使者- 發表於 5-4-2011 16:50

=口=..
唔係無限loop落去既咩..
唔用sum of infinite 有可能得咩..

-終場ソ使者-

你點樣想像到用無限有關呢?