1
$\begingroup$

To reduce theft among employees, a company subjects all employees to lie-detector tests and then res all employees failing this test. In the past, the test has been proven to correctly identify guilty employees 95% of the time; however 8% of the innocent also fail the test. Suppose that 20% of the employees are actually guilty.

What percentage of employees fail the test? What percentage of those fired were innocent?

  • 5
    http://en.wikipedia.org/wiki/Bayes'_theorem2011-09-21
  • 1
    It's worth noting, though irrelevant to your problem, that 95% is much higher and 8% much lower than the actual rates for polygraph tests. No comment on the 20%!2011-09-21

1 Answers 1