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Chapter 7: Probability
Figure 7-19:
Venn diagram displaying the restricted
Sample Space of event
V
for
Example 7-21
Multiplication Rule
Sometimes we rewrite the conditional probability relationship and refer to it
as the Multiplication Rule.
Rule 9
(multiplication rule for two dependent events): If events A and
B
are
dependent, then
P
(
A
B
) =
P
(
A
)
P
(
B
|
A
)
or
P
(
A
B
) =
P
(
B
)
P
(
A
|
B
).
Example 7-22:
In a random sample of 100 college students, 83 said they
have a laptop lease from their university. In addition, it is known that the
probability of a student owning a smart phone
given
that the student has a
laptop lease from the university is 0.62. What is the probability that a
randomly selected student from this sample will have a laptop lease and also
own a smart phone?