Section 7.5 – Conditional Probability
1
Section 7.5
Conditional Probability
Example 1:
Two cards are drawn without replacement in succession from a wellshuffled
deck of 52 playing cards.
What is the probability that the second card drawn is an ace,
given that the first card drawn was an ace?
The previous example is an example of conditional probability.
Conditional Probability of an Event
If A and B
are events in an experiment and P(A)
≠
0, then the conditional probability that
the event B will occur given that the event A has already occurred is
)
(
)
(
)

(
A
P
B
A
P
A
B
P
I
=
Example 2:
Given P(E) = 0.26, P(F) = 0.58, and P(E
I
F) = 0.02.
Find P(EF).
Example 3:
Given P(E
U
F
c
)
c
= 0.37, P(F
c
) = 0.61 and P(E) = 0.27.
Find P(F
c
E
c
).
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View Full DocumentSection 7.5 – Conditional Probability
2
Example 4:
A pair of fair dice is cast.
What is the probability that the sum of the
numbers falling uppermost is 6, if it is known that exactly one of the numbers is a 2?
Example 5:
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 Fall '10
 AbdelnourAhmedZaid
 Math, Conditional Probability, Probability, Probability theory

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