概率問題 有三條問題。她答對每條問題的概率是2/3，

1. P(答錯一題)

= [2/3 X 2/3 X (1 – 2/3)] X 3

= 4/9

2. P(答錯全部)

= (1 – 2/3) X (1 – 2/3) X (1 – 2/3)

= 1/27

3. P(最少答錯一題)

= 1 – P(全部答對)

= 1 – (2/3 X 2/3 X 2/3)

= 1 – 8/27

= 19/27

2007-11-25 17:56:53 補充：
3. P(最少答對一題) = 1 – P(全部答錯) = 1 – 1/27 (b part)= 26/27

第 3題, 樓上好似錯左

P(最少答對一題)
= 1- P(全部答錯)
=1- 1/3 x 1/3 x 1/3
=1- 1/27
=26/27 //

1. (1/3*2/3*2/3)*3
2. 1/3*1/3*1/3
3. (1/3*1/3*2/3)*3+(1/3*2/3*2/3)*3+2/3*2/3*2/3



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