更新1:
Answer in rational number.
Probability
2010-09-02 6:56 am
Peter throws 3 balls one by one into a basket. Probability that he can throw a ball into the basket in the first throw is 0.5. For each subsequent trial, the probability of success is 0.5(0.25)^n, where n is the number of previous unsuccessful trials. What is the probability that he gets 2 balls in the basket?
回答 (1)
2010-09-02 7:42 am
✔ 最佳答案
P(he gets 2 balls in the basket)= P(success success unsuccess) + P(success unsuccess success)+ P(unsuccess success success)= 0.5 * 0.5(0.25)^0 * [1 - 0.5(0.25)^0] + 0.5 * [1 - 0.5(0.25)^0] * 0.5(0.25)^1
+ 0.5 * 0.5(0.25)^1 * 0.5(0.25)^1= 0.5 * 0.5 * 0.5 + 0.5 * 0.5 * 0.125 + 0.5 * 0.125 * 0.125= 0.125 + 0.03125 + 0.0078125= 0.1640625= 21/128
收錄日期: 2021-04-21 22:19:43
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100901000051KK01690