Probability of event: Should she drop English course?

[weltyj]

Jenny is taking courses in both math and english....she estimates her probability of passing math at .4, english at .6, and the probability of passing at least one of them is .8. After midterm exams, she reassesses her probability of passing math to .7. She feels her probability of passing at least one of these courses is still .8, but she has a probability of only .1 of passing both courses. If her probability of passing english is less than .4, she will drop english. Should she drop english? Why?

 

[royhaas]

Ignore "before mid-term". Use the formula for the probability of the union of two events, i.e., the probability that she will pass at least one course.