Question

概率 英文的36个人来自于两个家庭.其中25个姓李,11个姓陈.25个李姓人中,有4个单身男,5个单身女,和8对新人.1

Answer 1

1.find the probability that they are married to each other.

==[(C1--8）+(C1--3）]/(C2--36)=11/(36*35/2)=11/630;

2.find the probability that they both have named Lee,given that they are married to each other.

===(C1--8)/(C2--36)=8/(36*35/2)=4/315;

3.find the probability that they are a man and a women with the same name.

=【{[C1--4]*[C1--5]+8}+{[C1--2]*[C1--3]+3}】/(C2-36)

=[20+8+6+3]/(36*35/2)=37/630;

4.find the probability that they are married to each other,given that they are a man and a woman with the same name.

P of lee=[C1--8]/(C2-25)=8/(25*24/2)=2/75;

P of chen=[C1--3]/(C2-11)=3/(11*10/2)=3/55;

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