Assume the only grades possible in a history course are a, b, c, or lower than c. the probability that a randomly selected student will get an a in the course is 0.46, the probability that a student will get a b in the course is 0.17, and the probability that a student will get a c in the course is 0.23. a. what is the probability that a student will get an a or a b? b. what is the probability that a student will get an a or a b or a c? c. what is the probability that a student will get a grade lower than a c?