A probability question..

Here's the question:

At a certain stage of a criminal investigation, the inspector in charge is 60% convinced of the guilt of a certain suspect. Suppose now that a new piece of evidence that shows that the criminal has a certain characteristic (such as left-handedness, baldness, brown hair, etc.) is uncovered. If 20% of the population possesses this characteristic, how certain of the guilt of the suspect should the inspector now be if it turns out that the suspect has this characterstic?

I have an exam next week on probability and random processes, and I can't solve this question, any ideas?

What a retarded word problem. Criminal investigations do not work that way. You don't go to jail if you rack up a "100%" suspicion of guilt. Plus, the initial "60%" (as well as the relative importance of the undefined new evidence) is completely arbitrary, subjective, and without perspective.

There is no answer to the stated question because it makes no fucking sense. Drop out of school now and learn to flip burgers, retard.