Re: [理工] [機率]-機率

[swon ()]

※ 引述《AAJJBurnett (叫我投手)》之銘言：
:  suppose that ther are 14 songs on a compact disk(CD) and you like 8
:  of them. When using the random button selector on a CD player , each
:  of the 14 songs is played once in a random order .Find the probability
:  that among the first 2 songs that are played,

   畫樹狀圖：
                           7
                         ----- 喜歡第二首
                          13
                        /
                  8    /
   喜歡第一首   -----
                 14    \
                        \
                           6
                         ----- 不喜歡第二首
                          13

                           8
                         ----- 喜歡第二首
                          13
                        /
                   6   /
   不喜歡第一首  -----
                  14   \
                        \
                           5
                         ----- 不喜歡第二首
                          13

:  (a)You like both of them

      = (8/14)(7/13) = 56/182 (30.77%)

:  (b)You like neither of them

      = (6/14)(5/13) = 30/182 (16.48%)

:  (c)You like exactly one of them

      = (8/14)(6/13) + (6/14)(8/13) = 48/182 + 48/182 = 96/182 (52.75%)

     (Check加起來的機率和是一)

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※ 編輯: swon            來自: 114.32.231.74        (09/29 16:36)