Assume that 30 percent of computer owners employ a Macintosh, 50 percent use Windows, and 20 percent use Linux. Assume that 65 percent of the Mac users have succumbed to a computer virus, 82 percent of the Windows users get the virus, and 50 percent of the Linux users get the virus. We choose a person at random and learn that her system was infected by the virus. What is the probability that she is a Windows user?