PROBABILITY
Intersection and conditional:
Suppose that a certain college class contains 36 students. Of these, 19 are freshmen, 23 are economics majors, and 12 are neither. A student is selected at random from the class.
(a) What is the probability that the student is both a freshman and an economics major?
(b) Given that the student selected is a freshman, what is the probability that she is also an economics major? Write your responses as fractions. (If necessary, consult a list of formulas.)