The article “FBI Says Fewer than 25 Failed Polygraph Test” (San Luis Obispo Tribune, July 29, 2001) states that falsepositives in polygraph tests (tests in which an individual fails even though he or she is telling the truth) are relatively common and occur about 15% of the time. Let x be the number of trustworthy FBI agents tested until someone fails the test.
a. Is the probability distribution of x binomial or geometric?
b. What is the probability that the first false positive will occur when the third agent is tested?
c. What is the probability that fewer than four are tested before the first false positive occurs?
d. What is the probability that more than three agents are tested before the first false positive occurs? Sect ion 6.7 Exercise Set 2