假設金是個正常人 小傑也是個正常男孩子
當小傑找到金時
金跟小傑說除了小傑之外他在這世上還有一個孩子
請問金有兩個兒子的機率是多少?
(A)1/2
(B)1/3
這題跟條件機率有關
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※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 114.24.7.87
→
11/17 23:13, , 1F
11/17 23:13, 1F
→
11/17 23:18, , 2F
11/17 23:18, 2F
→
11/17 23:18, , 3F
11/17 23:18, 3F
→
11/17 23:23, , 4F
11/17 23:23, 4F
推
11/17 23:24, , 5F
11/17 23:24, 5F
推
11/17 23:25, , 6F
11/17 23:25, 6F
推
11/17 23:29, , 7F
11/17 23:29, 7F
→
11/17 23:32, , 8F
11/17 23:32, 8F
→
11/17 23:38, , 9F
11/17 23:38, 9F
推
11/17 23:58, , 10F
11/17 23:58, 10F
謝了 改一下題目
※ 編輯: gologo 來自: 114.24.7.87 (11/18 00:01)
推
11/18 00:11, , 11F
11/18 00:11, 11F
推
11/18 01:35, , 12F
11/18 01:35, 12F
推
11/18 01:38, , 13F
11/18 01:38, 13F
→
11/18 01:43, , 14F
11/18 01:43, 14F
→
11/18 01:43, , 15F
11/18 01:43, 15F
→
11/18 02:42, , 16F
11/18 02:42, 16F
推
11/18 03:15, , 17F
11/18 03:15, 17F
推
11/18 05:59, , 18F
11/18 05:59, 18F
→
11/18 06:39, , 19F
11/18 06:39, 19F
→
11/18 06:40, , 20F
11/18 06:40, 20F
題目第一句話 假設金是個正常人 即表示生下生男生女機率各趨近50%
不考慮有生下第三性的可能
推
11/18 07:13, , 21F
11/18 07:13, 21F
→
11/18 07:16, , 22F
11/18 07:16, 22F
推
11/18 08:48, , 23F
11/18 08:48, 23F
※ 編輯: gologo 來自: 114.45.190.31 (11/18 11:07)
推
11/18 13:27, , 24F
11/18 13:27, 24F
跟別人討論過的解法是
設X為金的兒子數量
X~B(2,1/2)
P(X=2)=1/4 P(X=1)=1/2
P(X=2|X>0)
=P(X=2)/P(X=1)+P(X=2)
=1/4/(1/4+1/2)
=1/4/3/4
=1/3
題目若只是問金生第二個孩子是兒子的機率 答案才是1/2
不知以上解釋有沒有問題?
※ 編輯: gologo 來自: 114.45.188.229 (11/18 15:20)
推
11/18 15:41, , 25F
11/18 15:41, 25F
→
11/18 15:41, , 26F
11/18 15:41, 26F
P(X=1,2)是表示金至少有一個兒子(指小傑這個兒子) 所以X不能是0
※ 編輯: gologo 來自: 114.45.188.229 (11/18 15:47)
推
11/18 15:49, , 27F
11/18 15:49, 27F
→
11/18 15:50, , 28F
11/18 15:50, 28F
→
11/18 15:50, , 29F
11/18 15:50, 29F
→
11/18 15:52, , 30F
11/18 15:52, 30F
→
11/18 15:53, , 31F
11/18 15:53, 31F
→
11/18 15:53, , 32F
11/18 15:53, 32F
→
11/18 15:54, , 33F
11/18 15:54, 33F
→
11/18 15:55, , 34F
11/18 15:55, 34F
還有 36 則推文
還有 2 段內文
推
11/19 13:20, , 71F
11/19 13:20, 71F
推
11/19 16:18, , 72F
11/19 16:18, 72F
推
11/19 16:21, , 73F
11/19 16:21, 73F
推
11/19 18:05, , 74F
11/19 18:05, 74F
推
11/19 18:07, , 75F
11/19 18:07, 75F
→
11/19 18:09, , 76F
11/19 18:09, 76F
→
11/19 18:09, , 77F
11/19 18:09, 77F
→
11/19 18:09, , 78F
11/19 18:09, 78F
推
11/19 18:20, , 79F
11/19 18:20, 79F
→
11/19 18:21, , 80F
11/19 18:21, 80F
推
11/19 18:22, , 81F
11/19 18:22, 81F
→
11/19 18:22, , 82F
11/19 18:22, 82F
→
11/19 18:22, , 83F
11/19 18:22, 83F
推
11/19 18:25, , 84F
11/19 18:25, 84F
→
11/19 18:27, , 85F
11/19 18:27, 85F
→
11/19 18:27, , 86F
11/19 18:27, 86F
→
11/19 18:29, , 87F
11/19 18:29, 87F
→
11/19 18:30, , 88F
11/19 18:30, 88F
→
11/19 19:32, , 89F
11/19 19:32, 89F
→
11/19 19:32, , 90F
11/19 19:32, 90F
→
11/20 21:24, , 91F
11/20 21:24, 91F
→
11/20 21:26, , 92F
11/20 21:26, 92F
→
11/20 21:32, , 93F
11/20 21:32, 93F
→
11/20 21:33, , 94F
11/20 21:33, 94F
→
11/20 21:38, , 95F
11/20 21:38, 95F
→
11/20 21:39, , 96F
11/20 21:39, 96F
→
11/20 21:40, , 97F
11/20 21:40, 97F
→
11/20 22:23, , 98F
11/20 22:23, 98F
→
11/20 22:24, , 99F
11/20 22:24, 99F
推
11/21 17:16, , 100F
11/21 17:16, 100F
→
11/21 17:18, , 101F
11/21 17:18, 101F
→
11/21 17:19, , 102F
11/21 17:19, 102F
→
11/21 17:20, , 103F
11/21 17:20, 103F
→
11/21 17:21, , 104F
11/21 17:21, 104F
→
11/21 17:22, , 105F
11/21 17:22, 105F
噓
11/22 00:13, , 106F
11/22 00:13, 106F
→
11/22 00:13, , 107F
11/22 00:13, 107F
→
11/22 00:15, , 108F
11/22 00:15, 108F
噓
11/22 00:23, , 109F
11/22 00:23, 109F
→
11/22 00:24, , 110F
11/22 00:24, 110F
討論串 (同標題文章)