Practice Problems for Exam I (Chapters 1–4)
1. A particular airline has 10 a.m. ﬂights from Chicago to NY, Atlanta, and LA. Let
A
denote the event that the NY ﬂight is full and deﬁne events
B
and
C
analogously for
Atlanta and LA, respectively. Suppose
P
(
A
) = 0
.
6
,P
(
B
) = 0
.
5
,P
(
C
) = 0
.
4
,
and the
three events are independent. What is the probability that only the NY ﬂight is full?
A. 0.12
B. 0.88
C. 0.18
D. 0.10
E. 0.60
Answer: C.
The event “only NY ﬂight is full” =
A
∩
B
0
∩
C
0
.
Then
P
(
A
∩
B
0
∩
C
0
) =
P
(
A
)
P
(
B
0
)
P
(
C
0
) = (0
.
6)(1

0
.
5)(1

0
.
4) = 0
.
18
.
2. 1% of all individuals in a certain population are carriers of a particular disease. A di
agnostic test for this disease has a 90% detection rate for carriers and a 5% rate for
noncarriers. Suppose the test is applied independently to two diﬀerent blood samples
from the same randomly selected individual. What is the probability that both tests yield
positive result?
A. 0.01
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '07
 Parzen
 Compact Disc, randomly selected boards

Click to edit the document details