Probability
2011-04-09 10:51 pm
3 persons are to be randomly selected from 15 boys and 25 girls. Find the probability that all boys are selected given that they are of the same gender.
回答 (1)
2011-04-09 11:07 pm
✔ 最佳答案
P(E)= P(3boys) / [P(3 boys) + P(3 girls)]= 15C3 / (15+25)C3]
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15C3 / (15+25)C3 + 25C3 / (15+25)C3
=455 / 9880
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455/9880 + 2300/9880
=455 / 2755
=91/551
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110409000051KK00538