The university has a student population of 15,000, with 15% of them retaking the introductory statistics (STAT) course. During the summer session, an instructor teaching the introductory STAT course is interested to know a. What is the probability that at least 19 out of the 105 students in her class were repeating the course? [3 marks] b. What is the probability that at most 19 out of the 105 students in her class were repeating the course