1. A bag with 4 red balls and 4 blue balls. Find the probability of getting exactly 2 red balls in 5 draws without replacement?
2. A bag with 4 red balls, 4 blue balls and 4 black balls. Find the probability of getting exactly 2 red balls in 5 draws without replacement?
Probability
2010-06-13 9:31 pm
回答 (1)
2010-06-13 10:28 pm
✔ 最佳答案
1)P(exactly 2 red balls in 5 draws without replacement)
= (2 from 4 red) ways * (3 from 4 blue) ways / (5 from 8 balls) ways
= 4C2 * 4C3 / 8C5
= 6 * 4 / 56
= 3/7
2)
P( exactly 2 red balls in 5 draws without replacement)
= (2 from 4 red) ways * (3 from 8 non red) ways / (5 from 12 balls) ways
= 4C2 * 8C3 / 12C5
= 6 * 56 / 792
= 14/33
收錄日期: 2021-04-21 22:13:01
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100613000051KK00623