Practice Test 1 (mine)

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University of Houston *

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3339

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Statistics

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Feb 20, 2024

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PRINTABLE VERSION Practice Test 1 You scored 93.75 out of 100 Question 1 Your answer is CORRECT. True or False: The cumulative frequency of a class is the total of all class frequencies up to but not including the frequency of the present class. a) True b) False Question 2 Your answer is CORRECT. A survey was conducted to gather ratings of the quality of service at local restaurants. Respondents rated on a scale of 0 (terrible) to 100 (excellent). The data are represented by the following stem plot. The mean of these data is a) cannot be determined b) equal to the median c) greater than the median d) less than the median Question 3 Your answer is CORRECT. The figure below shows a cumulative relative frequency histogram of 40 scores on a test given in a

Statistics class. Which of the following conclusions can be made from the graph? a) There is greater variability in the lower 20 test scores than in the higher 20 test scores. b) Sixty percent of the students had a test score above 80. c) The median test score is less than 70. d) The horizontal nature of the graph for test scores of 60 and below indicates that those scores occurred most frequently. Question 4 Your answer is CORRECT. A researcher randomly selects 4 fish from among 10 fish in a tank and puts each of the 4 selected fish into different containers. How many ways can this be done? a) 5040 b) 160 c) 1260 d) 25200 e) 20160 f) None of the above Question 5 Your answer is CORRECT. In a shipment of 59 vials, only 14 do not have hairline cracks. If you randomly select 2 vials from the shipment, what is the probability that all 2 of the selected vials have hairline cracks?

a) 0.4214 b) 0.0563 c) 0.5786 d) 0.9500 e) 0.0500 f) None of the above Question 6 Your answer is CORRECT. The union of two events A and B is the event that: a) The intersection of A and B does not occur. b) A and B occur at the same time. c) Either A or B, but not both occur. d) Both A and B occur. e) Either A or B or both occur. f) None of the above Question 7 Your answer is CORRECT. The probability that a randomly selected person has high blood pressure (the event H) is P(H) = 0.2 and the probability that a randomly selected person is a runner (the event R) is P(R) = 0.4. The probability that a randomly selected person has high blood pressure and is a runner is 0.1. Find the probability that a randomly selected person is a runner, given that he has high blood pressure. a) 0 b) 0.25 c) 1 d) 0.50

e) 0.17 f) None of the above. Question 8 Your answer is INCORRECT. The probability that a student correctly answers on the first try (the event A) is P(A) = 0.4. If the student answers incorrectly on the first try, the student is allowed a second try to correctly answer the question (the event B). The probability that the student answers correctly on the second try given that he answered incorrectly on the first try is 0.5. Find the probability that the student correctly answers the question on the first or second try. a) 0.20 b) 0.90 c) 0.64 d) 0.70 e) 0.65 f) None of the above. Question 9 Your answer is CORRECT. Hospital records show that 12% of all patients are admitted for heart disease, 16% are admitted for cancer (oncology) treatment, and 4% receive both coronary and oncology care. What is the probability that a randomly selected patient is admitted for coronary care, oncology or both? (Note that heart disease is a coronary care issue.) a) 0.28 b) 0.24 c) 0.72 d) 0.20 e) 0.32 f) None of the above. Question 10

Your answer is CORRECT. Given the following sampling distribution: X -16 -12 -7 10 19 P(X) 1 / 100 1 / 50 9 / 100 3 / 50 ___ What is P(X = 19)? a) 0.84 b) 0.80 c) 0.82 d) 0.19 e) 0.83 f) None of the above Question 11 Your answer is CORRECT. A store sells only two brands of sofas. One of the brands is currently advertised as on sale. The advertisers know that out of the people who come to the store to buy a sofa, every 1 out of 3 will buy the more expensive brand as opposed to the one in the sale advertisement. Let X = price of next sofa sold. What is the expected price of the sofa (E[X]) if the advertised sofa is $200 and the more expensive sofa is $375? a) 316.67 b) 258.33 c) 258.66 d) 243.75 e) 287.50 f) None of the above Question 12 Your answer is CORRECT.

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