Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

Exercise 45

Critical Thinking According to the college register's office, 40% of students enrolled in an introductory statistical class this semester are freshmen, 25% are sophomores, 15% are juniors, and 20% are seniors. You want to determine the probability that in a random sample of five students enrolled in introductory statistics this semester, exactly two are freshmen.
(a) Describe a trail. Can we model a trial as having only two outcomes If so, what is success What is failure What is the probability of success
(b) We are sampling without replacement. If only 30 students are enrolled in introductory statistics this semester, is it appropriate to model 5 trails as independent, with the same probability of success on each trail Explain. What other probability distribution would be more appropriate in this setting