作者Ertkkpoo (water)
看板Eng-Class
标题[请益] 数学题(统计)翻译
时间Mon Oct 24 23:21:14 2011
大家好
有两个问题想请教一下，我只列出题目，没有列问题，因为我的疑问只是在题意部分
1.
To reduce theft, the Merdeth Company screens all its employees with
a lie detector test that is known to be correct 90 percent of the time
(for both guility and innocent subjects). George Meredeth decides to fire
all employees who fail the test. Suppose 5 percent of the employees are
guility of theft.
问题见黄句，我不太懂这句的意思是不是指 机器会有90%的准确机会去找出
真正说谎者，而10%机会可能会误把无辜者判断为说谎者?
也就是我可以列式成 P(判为说谎者|真正说谎者)=90%?
P代表机率，上述表示法为条件机率
2.
A diagnostic test for a disease is said to be 99% accurate in that
if a person has the disease, the test will detect it with probability 0.9.
Also, if a person does not have the disease, the test will report that he
or she does not have it with probability 0.9. Only 1% of the population
has the disease in question. If a person is chosen at random from the
population and the diagnostic test indicates that she has the disease,
黄句的意思是不是指 P(被检查出有病|真正有病)=0.9? 但那个99%又是指?
谢谢大家
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1F：推 l10nel:1: 记得题目説both，所以除了说谎者的条件机率，还有： 10/25 04:24
2F：→ l10nel:P(判为説实话|真正说实话者)=90%，两式皆成立 10/25 04:25
3F：→ l10nel:2: 你说对了，和1一样的情况。99%指P(无病)=99%，或者 10/25 04:27
4F：→ l10nel:P(有病)=1%，两者是补集。 10/25 04:28
5F：→ dunchee:2. 如果你没有抄错，那麽就是原出处有问题 99% <-> 0.99 10/26 02:59
7F：推 l10nel:的确，第二题的「99% accurate」应改为90% 10/26 06:55
8F：→ Ertkkpoo:谢谢大家，可能是题目有问题，看了好久还是不懂题意 10/26 19:36
9F：→ l10nel:题目叙述应该不难吧，还有哪里不懂？还是不知怎麽解题？ 10/27 02:32