概率题目请指教，谢谢。

来源: pittsburgh 于 2016-05-08 19:10:47 [] [旧帖] [给我悄悄话] 阅读数 : (151 bytes)

The passing rate for a license exam is 87%, what is the probability that a person will not pass it until his or her second or third attempt?

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• 0.127803 -jinjing- ♀ 给 jinjing 发送悄悄话 (38 bytes) () 05/11/2016 postreply 10:50:34

• 非常感谢。　可否稍微解释一下？　 -pittsburgh- ♀ 给 pittsburgh 发送悄悄话 (23 bytes) () 05/21/2016 postreply 05:41:22

• 试详答. -jinjing- ♀ 给 jinjing 发送悄悄话 (376 bytes) () 05/22/2016 postreply 07:28:38

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