F 5 Maths 概率
回答 (6)
2014-03-18 3:05 am
✔ 最佳答案
因為只能在錢包中取出兩枚硬幤只有以下情況才能令兩枚的總值大於$2.6
1枚一元+1枚二元
2枚二元
硬幣總數=2+3+2=7
概率
= [(3C1‧2C1)+(2C2)] / (7C2)
= (6+1) / 21
= 1/3
3C1 = 從3枚一元硬幣中取出1枚一元硬幣
2C1 = 從2枚二元硬幣中取出1枚二元硬幣
2C2 = 從2枚二元硬幣中取出2枚二元硬幣
7C2 = 從7枚硬幣中取出2枚硬幣
2014-03-17 19:39:38 補充：
很好的例子~
值得參考
=]
2014-03-17 19:44:44 補充：
批卷貓提供了一些值得參考的例子
http://hk.knowledge.yahoo.com/question/question?qid=7014011400230
http://hk.knowledge.yahoo.com/question/question?qid=7014011700083
2014-04-26 8:49 am
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2014-04-11 5:56 am
>快去這里*****我每次都是去這里看
乞僵伭佫俧
乞僵伭佫俧
2014-04-08 11:12 am
>這里很不錯ａａａｓｈｏｐｓ。ｃｏｍ老婆很喜歡
卅僠
卅僠
2014-03-18 4:27 am
Probability of drawing a 1 dollar coin = 3/7.
Probability of drawing a 2 dollar coin = 2/7.
For total value to be greater than $2.60, it should be two 2 dollar coins or one 1 dollar coin and one 2 dollar coin.
P(2 dollar coin in 1st draw and 2 dollar coin in 2nd draw) = (2/7)(1/6) = 1/21.
P(2 dollar coin in 1st draw and 1 dollar coin in 2nd draw) = (2/7)(3/6) = 1/7.
P(1 dollar coin in 1st draw and 2 dollar coin in 2nd draw) = (3/7)(2/6) = 1/7.
So total probability = 1/21 + 1/7 + 1/7 = 7/21 = 1/3.
Probability of drawing a 2 dollar coin = 2/7.
For total value to be greater than $2.60, it should be two 2 dollar coins or one 1 dollar coin and one 2 dollar coin.
P(2 dollar coin in 1st draw and 2 dollar coin in 2nd draw) = (2/7)(1/6) = 1/21.
P(2 dollar coin in 1st draw and 1 dollar coin in 2nd draw) = (2/7)(3/6) = 1/7.
P(1 dollar coin in 1st draw and 2 dollar coin in 2nd draw) = (3/7)(2/6) = 1/7.
So total probability = 1/21 + 1/7 + 1/7 = 7/21 = 1/3.
2014-03-18 3:31 am
HK~
可能 Lily 不會看意見欄～
你可以補充回答貼上以下兩個連結給她參考一下～
http://hk.knowledge.yahoo.com/question/question?qid=7014011400230
http://hk.knowledge.yahoo.com/question/question?qid=7014011700083
大家努力！
2014-03-17 19:42:03 補充：
其實 drawing without replacement 的逐個分數乘，其實即係做緊 nCr 的計算，不過同學未必一定明白，所以兩個solutions都睇睇比較好～
可能 Lily 不會看意見欄～
你可以補充回答貼上以下兩個連結給她參考一下～
http://hk.knowledge.yahoo.com/question/question?qid=7014011400230
http://hk.knowledge.yahoo.com/question/question?qid=7014011700083
大家努力！
2014-03-17 19:42:03 補充：
其實 drawing without replacement 的逐個分數乘，其實即係做緊 nCr 的計算，不過同學未必一定明白，所以兩個solutions都睇睇比較好～
收錄日期: 2021-04-25 22:40:12
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20140317000051KK00123