SOLUTION: A diagnostic test for a certain disease is said to be 90% accurate in that, if a person has the disease, the test will detect with probability 0.9. Also, if a person does not hav

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Question 1151438: A diagnostic test for a certain disease is said to be 90% accurate in that,
if a person has the disease, the test will detect with probability 0.9. Also, if
a person does not have the disease, the test will report that he or she doesn’t
have it with probability 0.9. Only 1% of the population has the disease in
question. If the diagnostic test reports that a person chosen at random from
the population has the disease, what is the conditional probability that the
person, in fact, has the disease?

Answer by Boreal(15235)   (Show Source): You can put this solution on YOUR website!
Look at 10000 people
100 have the disease
--- D+ D- Total
T+ 90 990 1080
T- 10 8910 8920
Total 100 9900 10000
If the test is positive, the probability of having the disease is 90/1080 or 8.3%

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