Betty has 3 bags of balls.
BagA:3white ball and 2 red balls
B:2white ball and 3 blue balls
C:1 red ball
After drawing a ball,she puys the ball back to the original bag. Then she draws another ball from a randomly selected bag.What is the probability that both balls drawn are red and they come from the same bag?
Probability02
2009-10-14 4:37 am
回答 (3)
2009-10-14 4:56 am
✔ 最佳答案
P(both balls drawn are red and they come from the same bag)
= P(BagA red twice) + P(BagC twice)
= [(1/3)(3/5)]^2 + (1/3)^2
= 1/25 + 1/9
= 34 / 225
2009-10-13 21:03:24 補充：
Corrections :
P(both balls drawn are red and they come from the same bag)
= P(BagA red twice) + P(BagC twice)
= [(1/3)(2/5)]^2 + (1/3)^2
= 4/225 + 1/9
= 29 / 225
Thanks for nelsonywm2000 .
2009-10-21 5:01 am
2009-10-14 4:59 am
Only 2 red balls in A
收錄日期: 2021-04-21 22:03:41
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20091013000051KK01400