Jane is taking two courses. The probability she gets an A in the first course is 0.7. The probability she she gets an A in the second course is 0.8. The probability she gets an A in at least one of the courses is 0.9. What is the probability of passing at least one?
So you have 2 courses, 70% of A for course one, and 80% for course 2, and 90% chance to pass at least one? That doesn't make sense... also, I'm not sure about what a passing grade is, and there is also insufficent information to determine the answer. At least that's what I think. Sorry I couldn't help you!