Review Exercises 183 39. You are given that P1A2 = 0.15 and P1B2 = 0.40. Do you have enough information to find P1A or B2? Explain. 40. You are given that P1A or B2 = 0.55 and P1A2 + P1B2 = 1. Do you have enough information to find P1A and B2? Explain. Section 3.4 In Exercises 41– 44, perform the indicated calculation. 41. 11P2 42. 8P6 43. 7C4 44. 5C3 10C3 In Exercises 45–48, use combinations and permutations. 45. Fifteen cyclists enter a race. How many ways can the cyclists finish first, second, and third? 46. Five players on a basketball team must each choose one of the five players on the opposing team to defend. In how many ways can the players choose their defensive assignments? 47. A literary magazine editor must choose 4 short stories for this month’s issue from 17 submissions. In how many ways can the editor choose this month’s stories? 48. An employer must hire 2 people from a list of 13 applicants. In how many ways can the employer choose to hire the two people? In Exercises 49–53, use counting principles to find the probability. 49. A full house consists of three of one kind and two of another kind. You are dealt a hand of five cards from a standard deck of 52 playing cards. Find the probability of being dealt a full house consisting of three kings and two queens. 50. A security code consists of three letters and one digit. The first letter cannot be A, B, or C. What is the probability of guessing the security code on the first try? 51. A shipment of 200 calculators contains 3 defective units. What is the probability that a sample of three calculators will have (a) no defective calculators? (b) all defective calculators? (c) at least one defective calculator? (d) at least one nondefective calculator? 52. A class of 40 students takes a statistics exam. The results are shown in the table at the left. Three students are selected at random. What is the probability that (a) all three students received an A? (b) all three students received a C or better? (c) all three students received a D or an F? (d) all three students received a B or a C? 53. A corporation has six male senior executives and four female senior executives. Four senior executives are chosen at random to attend a technology seminar. What is the probability of choosing (a) four men? (b) four women? (c) two men and two women? (d) one man and three women? Letter grade Number of students A 8 B 10 C 12 D 6 F 4 TABLE FOR EXERCISE 52
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