肠子都段了，我终于做出来了

来源: 于 2010-04-01 09:46:33 [旧帖] [给我悄悄话] 本文已被阅读：次

1. for years of experience, she estimates that the probability is 0.025 that an applicant will not bbe able to repay her installment loan. Last month she made 40 loans.
a. what is the probabliity that 3 loans will be defaulted?
2. what is the probability that at least 3 loans will be defaulted?


answer:

1. 0.025 * 0.025 * 0.025;
2. 0.0.25^3 + 0.025^4 + ... + 0.025^40