1.
A box contains 3 yellow chips.2 red chips and 1 white chip.If a chip is drawn at radom from the box without replacement until a yellow chip is drawn .Find the probability that at most 3 attempts are needed.
2.
If the probabilities that Anita will pass in Chinese,Englishand Mathematics tests are 3/4,2/3 and 3/5 respectively,what is the probability that she will pass exactly two of these three subjects?
More about probability
2011-04-24 8:23 pm
回答 (1)
2011-04-24 8:42 pm
✔ 最佳答案
1 Let the no. of draw needed is X, P(X<=3)
= (3/6) + (3/6)(3/5) + (3/6)(2/5)(3/4)
= 1/2 + 9/30 + 6/40
= 19/20
2 Probability that she will pass exactly two of these three subjects
= (3/4)(2/3)(1 - 3/5) + (3/4)(1 - 2/3)(3/5) + (1 - 3/4)(2/3)(3/5)
= (3/4)(2/3)(2/5) + (3/4)(1/3)(3/5) + (1/4)(2/3)(3/5)
= 27/60
= 9/20
收錄日期: 2021-04-26 14:06:14
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110424000051KK00311