When you have completed your exam and reviewed your answers, click
When you have completed your exam and reviewed your answers, click Submit Exam. Answers will not be recorded until you hit Submit Exam. If you need to exit before completing the exam, click Cancel Exam. Questions 1 to 20: Select the best answer to each question. Note that a question and its answers may be split across a page break, so be sure that you have seen the entire question and all the answers before choosing an answer. 1. A new car salesperson knows that she sells a car to one customer out of 20 who enter the showroom. Find the probability that she’ll sell a car to exactly two of the next three customers. A. 0.9939 B. 0.0075 C. 0.1354 D. 0.0071 2. Approximately how much of the total area under the normal curve will be in the interval spanning 2 standard deviations on either side of the mean? A. 68.3% B. 99.7% C. 95.5% D. 50% 3. In the binomial probability distribution, p stands for the A. probability of failure in any given trial. B. number of trials. C. probability of success in any given trial. D. number of successes. 4. The area under the normal curve extending to the right from the midpoint to z is 0.17. Using the standard normal table on the textbook’s back endsheet, identify the relevant z value. A. –0.0675 B. 0.4554 C. 0.0675 D. 0.44 Protestant Catholic Jewish Other Democrat 0.35 0.10 0.03 0.02 Republican 0.27 0.09 0.02 0.01 Independent 0.05 0.03 0.02 0.01 5. The table above gives the probabilities of combinations of religion and political parties in a city in the United States. What is the probability that a randomly selected person will be a Protestant and at the same time be a Democrat or a Republican? A. 0.62 B. 0.89 C. 0.67 D. 0.35 6. Each football game begins with a coin toss in the presence of the captains from the two opposing teams. (The winner of the toss has the choice of goals or of kicking or receiving the first kickoff.) A particular football team is scheduled to play 10 games this season. Let x = the number of coin tosses that the team captain wins during the season. Using the appropriate table in your textbook, solve for P(4 ≤ x ≤ 8). A. 0.171 B. 0.246 C. 0.817 D. 0.377 7. From an ordinary deck of 52 playing cards, one is selected at random. What is the probability that the selected card is either an ace, a queen, or a three? A. 0.3 B. 0.25 C. 0.0769 D. 0.2308 8. Tornadoes for January in Kansas average 3.2 per month. What is the probability that, next January, Kansas will experience exactly two tornadoes? A. 0.2087 B. 0.2226 C. 0.1304 D. 0.4076 9. A breeder records probabilities for two variables in a population of animals using the two-way table given here. Let A be the event “shaggy and brown-haired.” Compute P(A c ). Brown-haired Blond Short-haired 0.06 0.23 Shaggy 0.51 0.20 A. 0.51 B. 0.36 C. 0.49 D. 0.77 10. Which of the following is a discrete random variable? A. The number of three-point shots completed in a college basketball game B. The average daily consumption of water in a household C. The weight of football players in the NFL D. The time required to drive from Dallas to Denver 11. An apartment complex has two activating devices in each fire detector. One is smoke-activated and has a probability of .98 of sounding an alarm when it should. The second is a heat-sensitive activator and has a probability of .95 of operating when it should. Each activator operates independently of the other. Presume a fire starts near a detector. What is the probability that both activating devices will work properly? A. 0.9895 B. 0.931 C. 0.049 D. 0.965 12. What is the value of ? A. 1.6 B. 6720 C. 56 D. 336 13. If event A and event B are mutually exclusive, P(A or B) = A. P(A) + P(B). B. P(A) + P(B) – P(A and B). C. P(A + B). D. P(A) – P(B). 14. Assume that an event A contains 10 observations and event B contains 15 observations. If the intersection of events A and B contains exactly 3 observations, how many observations are in the union of these two events? A. 0 B. 10 C. 22 D. 28 15. A breeder records probabilities for two variables in a population of animals using the two-way table given here. Given that an animal is brown-haired, what is the probability that it’s short-haired? Brown-haired Blond Short-haired 0.06 0.23 Shaggy 0.51 0.20 A. 0.222 B. 0.105 End of exam C. 0.0306 D. 0.06 16. The possible values of x in a certain continuous probability distribution consist of the infinite number of values between 1 and 20. Solve for P(x = 4). A. 0.03 B. 0.05 C. 0.02 D. 0.00 17. If the mean number of hours of television watched by teenagers per week is 12 with a standard deviation of 2 hours, what proportion of teenagers watch 16 to 18 hours of TV a week? (Assume a normal distribution.) A. 4.2% B. 0.3% C. 2.1% D. 4.5% 18. Using the standard normal table in the textbook, determine the solution for P(0.00 ≤ z ≤ 2.01). A. 0.1179 B. 0.0222 C. 0.4821 D. 0.4778 19. Let event A = rolling a 1 on a die, and let event B = rolling an even number on a die. Which of the following is correct concerning these two events? A. On a Venn diagram, event A would overlap event B. B. Events A and B are mutually exclusive. C. Events A and B are exhaustive. D. On a Venn diagram, event B would contain event A. 20. Which of the following is correct concerning the Poisson distribution? A. The event being studied is restricted to a given span of time, space, or distance. B. The mean is usually smaller than the variance. C. Each event being studied must be statistically dependent on the previous event. D. The mean is usually larger than the variance.