In a family with 4 children, assuming that boys and girls have an equal chance of being born.
(a)What is the probability that there are two boys and two girls.
(b)What is the probability that there is at least two girls.
I don't know if applying 1/2 is correct, I just suspect that this question is not that easy, so I post here.
Simon YAU
http://hk-math.com
Simple Probability
2012-01-27 7:35 pm
回答 (1)
2012-01-27 8:51 pm
✔ 最佳答案
a)P(there are two boys and two girls)= P(BBGG + BGBG + BGGB + GBBG + GBGB + GGBB)
= (4C2) (1/2)⁴
= 3/8
b)P(there is at least two girls)= P(there are two boys and two girls)
+ P(there are one boy and three girls)
+ P(there are four girls)
= 3/8
+ (4C3) (1/2)⁴
+ (4C4) (1/2)⁴
= 3/8 + 1/4 + 1/16
= 11/16
收錄日期: 2021-04-13 18:30:53
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120127000051KK00240