In a study of helicopter usage and patient survival, among the 49,075 patients transported by helicopter, 252 of them left the treatment center against medical advice, and the other 48,823 did not leave against medical advice. If 50 of the subjects transported by helicopter are randomly selected without replacement, what is the probability that none of them left the treatment center against medical advice?

Which of the following comparisons is true? a: high school tests generally cover more material than college exams. b: your college curriculum is more fixed and standardized than your high school curriculum. c: you get more personal attention in class from your college professors than from your high school teachers. d: college professors usually don't review test material in class the way high school teachers do.