A professor gives three possible types of exams, and her class does either well or badly. Suppose that the class does well on type 1, 2, and 3 exams with probabilities 0.3, 0.6, and 0.9, respectively. If the class does well on an exam, then the next exam is equally likely to be any of the three types. If the class does badly, then the next exam is always type 1. What proportion of exams are type 1, 2, and 3?