1.There are three children in a family.Assuming that the probability of having a boy is equal to that of having a girl,find the probability that
(a)all are boys
(b)there are two boys and one girl
Probability Question..
2007-12-20 5:21 am
回答 (2)
2007-12-20 7:36 pm
✔ 最佳答案
a. Utilize statistical method, it distributed as binary distributionaccording to the formula P(x)=nCx(p)x(1-p)n-x
where n (fixed number)=3, p (the probability of every success)=1/2, and x=3 (all are boys)
so P(3)=3C3(1/2)3(1- 1/2)3-3
P(3)=1 x (1/2)3 x 1=1/8
∴P(all are boys)=1/8
b. P(two boys & one girl)=P(2)=3C2(1/2)2(1- 1/2)3-2
=3(1/2)2(1/2)=3/8
∴P(two boys & one girl)=3/8
參考: me
2007-12-20 5:37 am
(a) P(All are boys) = 1/2 * 1/2 * 1/2 = 1/8
(b) P(2 boys and 1 girl) = 1/8 + 1/8 + 1/8 = 3/8
(b) P(2 boys and 1 girl) = 1/8 + 1/8 + 1/8 = 3/8
收錄日期: 2021-04-13 14:45:27
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