QUESTION 13 It has been shown that 85% of the devices made by a particular manufacturer are still working after ve years. If 15 devices are selected at random, what is the probability that at least 12 of them will be working after ve years? QUESTION 14 A student is taking a multiple choice quiz with 20 questions. Each question on the quiz has four choices (A, B, C, and D). The student has not studied and guesses at the answers. Each of the alternatives is equally likely. What is probability that the student will answer at least half of the questions correctly? QUESTION 15 The mortality rate for a certain disease is 70%. What is the probability that at least 10 out of 15 randomly selected patients with the disease will survive it