At the beginning of the semester, a professor tells students that if they study for the tests, then there is a 55% chance they will get a B or higher on the tests. If they do not study, there is a 20% chance that they will get a B or higher on the tests. The professor knows from prior surveys that 60% of students study for the tests. The probabilities are displayed in the tree diagram.
A tree diagram. Random student studies for test is 0.6, and does not study for test is 0.4. Studies for test to Gets B or higher is 0.55; does not get B or higher is 0.45. Does not study for test to Gets B or higher is 0.20; does not get B or higher is 0.80.
The professor informs the class that there will be a test next week. What is the probability that a randomly selected student passes the test with a B or higher?
0.33
0.41
0.55
0.75