從 1 - 49 個號碼中每次抽取 7 個不同號碼 , 然後放回 , 再進行下次抽取。
若至少抽取 n 次後 , 所有號碼均至少出現 1 次。
問題 :
1) 求 n 的最小值。
2) 求 n 的期望值。
~~六合彩的數學(3)~~ (骨灰級難度)
2012-02-19 12:45 am
回答 (6)
2012-03-04 3:40 am
✔ 最佳答案
這題應該是類似http://tw.knowledge.yahoo.com/question/question?qid=1011012505430的玩意。第二題應該是若干個超幾何分配的期望值之和。
2012-03-03 19:40:59 補充：
圖片參考：http://i212.photobucket.com/albums/cc82/doraemonpaul/yahoo_knowledge/crazyprobability/crazyprobability29.jpg
參考資料：
my wisdom of maths + http://tw.knowledge.yahoo.com/question/question?qid=1011012505430
2015-11-26 12:07 pm
25,29,20
2012-02-28 7:59 am
1.7次
2.infinitive
2.infinitive
2012-02-25 4:15 am
1. 7 次為最少值
2. No，好難解式，明就明唔明就唔明！
2. No，好難解式，明就明唔明就唔明！
2012-02-21 5:47 am
1) 7times
2) 無限
2) 無限
2012-02-20 6:44 pm
1) 7 times.
2) 無限
2012-02-22 10:43:45 補充：
49+48+47+46+45+44+43+42+41+.........+1 分之49
2012-02-22 12:06:33 補充：
No, 2) is 48*47*46*45*.......*2
2012-02-22 12:11:19 補充：
2) Not included of repeat
2012-02-22 13:09:57 補充：
No, 2) is 48*47*46*45*.......*2, but not included of repeat
2012-02-23 10:40:06 補充：
No, no. 2 CORRECT ANSWER:
49/49+48/49+47/49+46/49+......+2/49+1/49=1225/49=25
2)25 times
2012-02-27 13:15:38 補充：
It's have 49 numbers, and it'll have 42 numbers for the second time.
So, no.2 answer isn't correct.
It's :
42/49+41/49+......+2/49+1/49=1020/49= 20 40/49
2012-02-27 18:19:44 補充：
No repeat of first time
2) 無限
2012-02-22 10:43:45 補充：
49+48+47+46+45+44+43+42+41+.........+1 分之49
2012-02-22 12:06:33 補充：
No, 2) is 48*47*46*45*.......*2
2012-02-22 12:11:19 補充：
2) Not included of repeat
2012-02-22 13:09:57 補充：
No, 2) is 48*47*46*45*.......*2, but not included of repeat
2012-02-23 10:40:06 補充：
No, no. 2 CORRECT ANSWER:
49/49+48/49+47/49+46/49+......+2/49+1/49=1225/49=25
2)25 times
2012-02-27 13:15:38 補充：
It's have 49 numbers, and it'll have 42 numbers for the second time.
So, no.2 answer isn't correct.
It's :
42/49+41/49+......+2/49+1/49=1020/49= 20 40/49
2012-02-27 18:19:44 補充：
No repeat of first time
收錄日期: 2021-04-11 18:59:21
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120218000051KK02216