8) In a class half the students are science majors and half are liberal art majors. A student who is a science major has a 0.9 probability of passing a test whilst a student who is liberal art major has only a probability of 0.7. a) What is the probability that a randomly chosen student passes the exam? We chose with equal probability among all students. b) Out of a class of 20, what is the probability that all students pass the test?