3- David plays chess games against three other opponents (say, Alice, Bob, and Charlie in that

order). He has probability 0.6, 0.5, and 0.8 of winning each of these games, respectively. It is

reasonable to believe that events corresponding to winning each of these games are independent.

Given that David wins at least one of the first two games, what is the conditional probability that he

wins at least one of the last two?