A rare disease exists with which only 1 in 500 individuals is affected. A test for the disease exists, but of course, it is not infallible. A true-positive result (patient actually has the disease) occurs 95% of the time, while a false-positive result (patient does not have the disease) occurs 1% of the time.
If a randomly selected individual is tested and the result is positive, what is the probability that the individual doesn't have the disease?