A woman is trapped in a room at the center of a maze. The room has three exits. Exit 1 leads outside the maze after 3 minutes, on average. Exit 2 will bring her back to the same room after 5 minutes. Exit 3 will bring her back to the same room after 7 minutes. Assume that every time she makes a choice, she is equally likely to choose any exit. What is the expected time taken by her to leave the maze