Consider a lie detector called the Computerized Voice Stress Analyzer (CVSA). The manufacturer claims that the CVSA is 98% accurate and, unlike a polygraph machine, will not be thrown off by drugs and medical factors. However, laboratory studies by the U.S. Defense Department found that the CVSA had an accuracy rate of 49.8%, slightly less than pure chance. Suppose the CVSA is used to test the veracity of four suspects. Assume that the suspects' responses are independent.
a. If the manufacturer's claim is true, what is the probability that the CVSA will correctly determine the veracity of all four suspects?
b. If the manufacturer's claim is true, what is the probability that the CVSA will yield an incorrect result for at least one of the four suspects?
c. Suppose that in a laboratory experiment conducted by the U.S. Defense Department on four suspects, the CVSA yielded incorrect results for two of the suspects.
Make an inference about the true accuracy rate of the new lie detector.