1. 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
2. The probability of an offender having a speeding ticket is 35%, having a parking ticket is 44%, having
both is 12%. What is the probability of an offender having either a speeding ticket or a parking ticket or
3. 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(Ac).
Short-haired 0.06 0.23
Shaggy 0.51 0.20
4. A basketball team at a university is composed of ten players. The team is made up of players who play
the position of either guard, forward, or center. Four of the ten are guards, four are forwards, and two are
centers. The numbers that the players wear on their shirts are 1, 2, 3, and 4 for the guards; 5, 6, 7, and 8
for the forwards; and 9 and 10 for the centers. The starting five are numbered 1, 3, 5, 7, and 9. Let a
player be selected at random from the ten. The events are defined as follows:
Let A be the event that the player selected has a number from 1 to 8.
Let B be the event that the player selected is a guard.
Let C be the event that the player selected is a forward.
Let D be the event that the player selected is a starter.
Let E be the event that the player selected is a center.
5. 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?
6. 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?
7. If the probability that an event will happen is 0.3, what is the probability of the event's complement?
8. What is the value of ?
9. 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).
10. Tornadoes for January in Kansas average 3.2 per month. What is the probability that, next January,
Kansas will experience exactly two tornadoes?
11. 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?
12. 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).
13. 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 =
14. 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?
End of exam
15. 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.
16. For each car entering the drive-through of a fast-food restaurant, x = the number of occupants. In this
study, x is a
A. continuous quantitative variable.
B. discrete random variable.
C. dependent event.
D. joint probability.
17. Which of the following is correct concerning the Poisson distribution?
A. The mean is usually smaller than the variance.
B. The mean is usually larger than the variance.
C. The event being studied is restricted to a given span of time, space, or distance.
D. Each event being studied must be statistically dependent on the previous event.
18. A continuous probability distribution represents a random variable
A. having an infinite number of outcomes that may assume any number of values within an interval.
B. that's best described in a histogram.
C. that has a definite probability for the occurrence of a given integer.
D. having outcomes that occur in counting numbers.
19. 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.
20. Using the standard normal table in the textbook, determine the solution for P(0.00 = z = 2.01).