At a certain university, 30% of the students major in math. Of the students majoring in math, 60% are males. Of all the students at the university, 70% are males.
a) What is the probability that a student selected at random in the university is male and majors in math?
b) What is the probability that a randomly selected student in the university is female or majors in math or both?
I got a) as 18%, I am not sure how to do b).
There are 30 female students and 18 math majors who are not female (as
the female math majors have already been counted we don't count them
again), so there are 48 students who satisfy the criteria out of 100, so the
0probability is 48%.