In a survey of 700 freshmen, 300 were enrolled in a math course and 500 were enrolled in a writing course. Of those enrolled in the writing course, 210 weren't enrolled in a math course.
a. How many students in the survey were enrolled in neither a math course nor a writing course?
b. Suppose you are told that a freshman is enrolled in a writing course, what is the probability that he/she is enrolled in both math and writing course?
c. Are the events students enrolled in math course and writing course independent?