# A probability question

#### bryce09

##### New Member
I am trying to revise for a test, and am working through some prep questions. I am struggling on this one, could anyone help?

Suppose there is a medical diagnostic test for a disease. The sensitivity of the
test is .95. This means that if a person has the disease, the probability that the
test gives a positive response is .95. The specificity of the test is .90. This
means that if a person does not have the disease, the probability that the test
gives a negative response is .90, or that the false positive rate of the test is .10.
In the population, 1% of the people have the disease.
What is the probability that a person tested has the disease, given the results of the test is positive? Let
D be the event "the person has the disease" and let T be the event "the test
gives a positive result."

Any help would be much appreciated.

#### Dason

Do you know Bayes theorem?

#### bryce09

##### New Member
I do, im just getting muddled up with the wording of the question so I keep confusing myself