6.4 An investor tells you that in her estimation there
6.10 Refer to Exercise 6.9. Suppose that you believe that
6.5 The sample space of the toss of a fair die is
6.11 Shoppers can pay for their purchases with cash, a
is a 60% probability that the Dow Jones Industrial
Averages index will increase tomorrow.
a. Which approach was used to produce this figure?
b. Interpret the 60% probability.
S = 5 1, 2, 3, 4, 5, 6 6
If the die is balanced each simple event has the same
probability. Find the probability of the following
events.
a. An even number
b. A number less than or equal to 4
c. A number greater than or equal to 5
6.6 Four candidates are running for mayor. The four
candidates are Adams, Brown, Collins, and Dalton.
Determine the sample space of the results of the
election.
6.7 Refer to Exercise 6.6. Employing the subjec-
tive approach a political scientist has assigned the
­following probabilities:
P(Adams wins) = .42
P(Brown wins) = .09
P(Collins wins) = .27
P(Dalton wins) = .22
contractor 1 is twice as likely to win as contractor 3
and that contractor 2 is three times as likely to win
as contactor 3. What are the probabilities of winning for each contractor?
credit card, or a debit card. Suppose that the proprietor of a shop determines that 60% of her customers use a credit card, 30% pay with cash, and the
rest use a debit card.
a. Determine the sample space for this experiment.
b. Assign probabilities to the simple events.
c. Which method did you use in part (b)?
6.12 Refer to Exercise 6.11.
a. What is the probability that a customer does
not use a credit card?
b. What is the probability that a customer pays
in cash or with a credit card?
c. Which method did you use in part (b)?
6.13 A survey asks adults to report their marital status.
The sample space is
S = 5 single, married, divorced, widowed 6
Use set notation to represent the event the adult is
not married.
6.14 Refer to Exercise 6.13. Suppose that in the city in
Determine the probabilities of the following events.
a. Adams loses.
b. Either Brown or Dalton wins.
c. Adams, Brown, or Collins wins.
6.8 The manager of a computer store has kept track
of the number of computers sold per day. On the
basis of this information, the manager produced the
­following list of the number of daily sales.
Number of Computers Sold
Probability
0
1
2
3
4
5
.08
.17
.26
.21
.18
.10
a. If we define the experiment as observing
the number of computers sold tomorrow,
­determine the sample space.
b. Use set notation to define the event, sell more
than three computers.
c. What is the probability of selling five computers?
d. What is the probability of selling two, three, or
four computers?
e. What is the probability of selling six
computers?
6.9 Three contractors (call them contractors 1, 2, and 3)
bid on a project to build a new bridge. What is the
sample space?
which the survey is conducted, 50% of adults are
married, 15% are single, 25% are divorced, and
10% are widowed.
a. Assign probabilities to each simple event in the
sample space.
b. Which approach did you use in part (a)?
6.15 Refer to Exercises 6.13 and 6.14. Find the probabil-
ity of each of the following events.
a. The adult is single.
b. The adult is not divorced
c. The adult is either widowed or divorced.
6.16 There are 62 million Americans who speak a lan-
guage other than English at home. The languages
are Spanish, Chinese Tagalog (Philippines language), Vietnamese, French, Korean, and others.
Suppose that one of these individuals is selected at
random. Use set notation to list the sample space.