<p>One more twist now. It makes a question a far cry from the SAT, but more realistic.</p>
<p>One person in every 1000 of a population is known to have tuberculosis. When tested, there is a 95% chance that a person with tuberculosis will in fact register positive (not a very reliable test).
Furthermore, there is a 1% chance that a person with no tuberculosis will also register positive (makes the test even sloppier).
If a person tested positive, what are the chances that this person has tuberculosis?</p>
<p>I am getting 8.7% for an answer.</p>