a. No, because there are more students who do not have long hair than
students who do have long hair.
b. Yes, becatise there are more students with long hair wearing jeans, then
there are students who do not have long hair and wear jeans.
c. Yes, they are associated (not independent) because knowing if a student
wears jeans has changed our opinion.
d. No, becatise they can occur at the same time.