How many "true" terrorists are there in the US?  I don't know, but let's suppose that there are 3000 out of a total population of, say, 3,000,000.  That is, one person in 100,000 is the real deal and very scary.  Now consider the Dick Cheney approach to searching for them (also very scary):  pervasive telephone wire-tapping linked to advanced voice analysis software. The software can detect terrorists within the utterance of three words, after which it automatically calls the FBI.  Assume that the system is 99% accurate.  That is, if a true terrorist is on the line, the software will notify the FBI 99% of the time; whereas, for non-terrorists, it will call the FBI (in error) only 1% of the time.  Presumably no software today is so accurate, but who knows with what NSA is fiddling.  When the FBI gets a report from the system, what is the probability that it has found a true terrorist (round off to nearest answer as needed)?

1.                  0.99

2.                  0.98

3.                  0.66

4.                  0.33

5.                  0.01

6.                  0.001

7.                  0.0001

8.                  None of the above

9.                  All of the above

10.              I don't have a clue.