※ 引述《TCSSH ()》之銘言：
: 6.
: A patient takes a lab test and the result comes back either positive or
: negative. The test returns a correct positive result in 99% of the cases in
: which the disease is actually present, and a correct negative result in 98%
: of the cases in which the disease is not present. Furthermore,0.001 of all
: people have this cancer.
: (a) If a person is tested positive, what is the probability that this person
: has the cancer.
: (b) If a person takes two independent tests and both return positive results.
: What is the probability that this person has the cancer?
: (c) If a person takes two independent tests and only one returns positive
: result. What is the probability that this person has the cancer?
: 我的算法是：
: a). 0.1/100 x 99/100 =9.9/10000
: b). (0.1/100 x 99/100)+(0.1/100 x 99/100) =19.8/10000
: c). (0.1/100 x 99/100)+(0.1/100 x 2/100) = 10.1/10000
: 可以幫我看看我算的對不對嗎 謝謝
如果我沒會錯題目意思的話, 答案應該如下.
a). (0.001*99%)/(0.001*99%+0.999*2%)
b). (0.001*99%*99%)/(0.001*99%*99%+0.999*2%*2%)
c). (0.001*99%*1%)/(0.001*99%*1%+0.999*2%*98%)
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