肠子都段了，我终于做出来了

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

所有跟帖： 

• 谢谢！ -断肠人- ♀ (24 bytes) () 04/01/2010 postreply 09:51:27

• 靠，你知道答案在这里瞎起哄呀？ -planojw- ♂ (0 bytes) () 04/01/2010 postreply 09:53:12

• 你有答案，还问？ -433832795028- ♂ (0 bytes) () 04/01/2010 postreply 09:53:15

• 厉害！难怪你的id是串数字 -陡然- ♂ (0 bytes) () 04/01/2010 postreply 09:52:10

• 麻烦你也帮我算算今年底的道琼斯指数？先谢了！ -陡然- ♂ (0 bytes) () 04/01/2010 postreply 09:55:35

• 5000 -planojw- ♂ (16 bytes) () 04/01/2010 postreply 09:58:18

• 惟恐天下不乱 -陡然- ♂ (0 bytes) () 04/01/2010 postreply 10:05:59

• between 11000 and 12000 -433832795028- ♂ (0 bytes) () 04/01/2010 postreply 10:02:19

• 是算出来的还是拍脑袋拍出来的？ -陡然- ♂ (0 bytes) () 04/01/2010 postreply 10:06:47

• 算出来的; 用抓蛙算得 -433832795028- ♂ (0 bytes) () 04/01/2010 postreply 10:11:30

• 不过好像和答案不一样 .. -planojw- ♂ (0 bytes) () 04/01/2010 postreply 10:33:41

• 靠，你知道答案在这里瞎起哄呀？ -planojw- ♂ -陡然- ♂ (0 bytes) () 04/01/2010 postreply 10:42:32