1. 2 digits are chosen at random from the password 234543.Find the prob. that the 2 digits are different.
1 .13/18
2 .13/15
3 .4/5
4 .2/3
2. A bag contains three 0.5 coins,two 0.2 coins and 2 one-dollar coin,if two coins are drawn at random,find the prob. that the sum of two coins are worth $1.50.(what means by worth?)more than or equal to???
3. 6boys and 4 girls are chosen to form a committee of 3 persons,find the prob. that 2 girls and a boy is chosen.
(do I need to use a table or a tree diagram?)
What form it is,seem like higher level,do U think so?
Some MCs
2013-08-31 1:59 am
回答 (2)
2013-08-31 3:29 am
✔ 最佳答案
1. the prob.that the 2 digits are the same=2/6C2
=2/15
the prob.that the 2 digits are different
=1-(2/15)
=13/15
2. Required prob.
=(2*3)C2/7C2
=5/7
worth 係指equal to
3. Required prob.
=[(4C2)+(6C1)]/(10C2)
=12/45
=4/15
2013-08-30 19:32:32 補充：
呢d其實唔難,不過思路要清晰.
2013-08-30 19:36:58 補充：
如果用我果個寫法,C要比數字大一倍
2013-09-06 20:08:45 補充：
corr.
3. Required prob.
=[(4C2)*(6C1)]/(10C3)
=0.3
2013-09-05 10:51 pm
3. (4C2 6C1) / 10C3 = 0.3
收錄日期: 2021-04-20 14:13:39
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20130830000051KK00256