Unformatted text preview: 9: Suppose that a college determines the following distribution for X = number of courses taken by a full‐
time student this semester: Value of X 3 4 5 6 Probability 0.07 0.25 0.28 56. The probability for X = 4 is missing. What is it? A) 0.07 C) 0.40 B) 0.25 D) 0.50 57. What is the average number of courses full‐time students at this college take this semester? A) 4 classes C) 4.74 classes B) 4.26 classes D) 5 classes 58. What is the standard deviation of the number of courses full‐time students at this college take this semester? A) 0.89 classes B) 0.94 classes C) 1 class D) 23.36 classes 59. What is P(X > 4.74)? A) 0.25 B) 0.28 C) 0.53 D) Impossible to calculate, because X cannot be 4.74. 60. It is estimated that chemotherapy is successful 70% of the time in curing a particular type of cancer. Suppose that 4 patients with the given type of cancer are treated and let X be the number of them that are successfully cured. X 0 1 2 3 4 P(X = x) 0.01 0.08 0.27 0.40 0.24 What is the expected value of the number of patients that will be cured? A) 3 B) 2 C) 0.2 D) 2.78 E) 2.5 13 J Diaco Elements of Statistics I Supplemental Final Exam Review The Biology Department plans to recruit a new faculty member. Data collected by a different university on the 410 possible candidates are available. The Biology Department is debating whether to put a requirement of 10 years of teaching experience in the job advertisement. The available data on the candidates are shown below: Less than 10 years’ 10 or more years’ experience experience Total Male 178 112 290 Female 99 21 120 Total 277 133 410 61. What is the probability that a candidate has less than 10 years’ experience? 62. For each of the following scenarios, determine whether the binomial distribution is the appropriate distribution for the random variable X. A) A fair coin is flipped ten times. Let X = the number of times the coin comes up tails. B) A fair coin is flipped multiple times. Let X = the number of times the coin needs to be flipped until we see ten tails. C) A roulette wheel with one ball in it is turned six times. Let X = the number of times the ball lands on red. D) There are ten people in the room: five men and five women. Three people are to be selected at random to form a committee. Let X = the number of men on the three‐person committee. Use the following to answer questions 63–66: The proportion of students who own a cell phone on college campuses across the country has increased tremendously over the past few years. It is estimated that approximately 90% of students now own a cell phone. Fifteen students are to be selected at random from a large university. Assume that the proportion of students who own a cell phone at this university is the same as nationwide. Let X = the number of students in the sample of 15 who own a cell phone. 63. What is the appropriate distribution for X? A) X is N(15, 0.9) B) X is B(15, 0.9) C) X is B(15, 13.5) D) X is N(13.5, 1.16) 64. On average, how many students will own a cell phone in simple random samples of 15 students? A) 9 B) 13 C) 13.5 D) 14 65. A) B) C) D) What is the standard deviation of the number of students who own a cell phone in simple random samples of 15 students? 0.077 0.09 1.16 1.35 14 J Diaco Elements of Statistics I Supplemental Final Exam Review 66. A) B) C) D) W...
View Full Document
- Summer '09
- Statistics, J Diaco, Supplemental Final Exam