Exam_050272rr – probability_a breeder records probabilities for two

1. 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. 0.06
C. 0.0306
D. 0.105


2. 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. The mean is usually larger than the variance.
D. Each event being studied must be statistically dependent on the previous event.


3. If the probability that an event will happen is 0.3, what is the probability of the event’s complement?
A. 0.3
B. 0.1
C. 1.0
D. 0.7


4. The Burger Bin fast-food restaurant sells a mean of 24 burgers an hour and its burger sales are normally
distributed. The standard deviation is 3.061. What is the probability that the Burger Bin will sell 12 to 18
burgers in an hour?
A. 0.239
B. 0.136
C. 0.475
D. 0.342


5. What is the value of ?
A. 1.6
B. 56
C. 6720
D. 336


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
6. 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. 0.35
B. 0.62
C. 0.67
D. 0.89


7. Using the standard normal table on page 822 of the textbook, determine the solution for P(0.00 ≤ z ≤
A. 0.0222
B. 0.1179
C. 0.4821
D. 0.4778


8. If event A and event B are mutually exclusive, P(A or B) =
A. P(A) + P(B) – P(A and B).
B. P(A + B).
C. P(A) + P(B).
D. P(A) – P(B).


9. 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. –0.0675
C. 0.4554
D. 0.44


10. In the binomial probability distribution, p stands for the
A. probability of failure in any given trial.
B. probability of success in any given trial.
C. number of trials.
D. number of successes.


11. 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. 0.00
C. 0.05
D. 0.02


12. 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. 0.817
B. 0.171
C. 0.377
D. 0.246


13. Tornadoes for January in Kansas average 3.2 per month. What is the probability that, next January, Kansas will experience exactly two tornadoes?
A. 0.2226
B. 0.2087
C. 0.4076
D. 0.1304


14. A continuous probability distribution represents a random variable
A. that has a definite probability for the occurrence of a given integer.
B. having an infinite number of outcomes that may assume any number of values within an interval.
C. that’s best described in a histogram.
D. having outcomes that occur in counting numbers.


15. Find the z-score that determines that the area to the right of z is 0.8264.
A. 1.36
B. –1.36
C. –0.94
D. 0.94


16. The Burger Bin fast-food restaurant sells a mean of 24 burgers an hour and its burger sales are normally distributed. If hourly sales fall between 24 and 42 burgers 49.85% of the time, the standard deviation is _______ burgers.
A. 18
B. 9
C. 3
D. 6


17. 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. 0.931
B. 0.9895
C. 0.049
D. 0.965


18. 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 B would contain event A.
B. Events A and B are mutually exclusive.
C. On a Venn diagram, event A would overlap event B.
D. Events A and B are exhaustive.


19. A credit card company decides to study the frequency with which its cardholders charge for items from a certain chain of retail stores. The data values collected in the study appear to be normally distributed with a mean of 25 charged purchases and a standard deviation of 2 charged purchases. Out of the total number of cardholders, about how many would you expect are charging 27 or more purchases in this study?
A. 68.3%
B. 47.8%
C. 15.9%
D. 94.8%


20. For each car entering the drive-through of a fast-food restaurant, x = the number of occupants. In this study, x is a
A. dependent event.
B. joint probability.
C. continuous quantitative variable.
D. discrete random variable.


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