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Econ 41
Ekaterini Kyriazidou
UCLA
Statistics for Economists
Class 9: Practice Problems
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•
(Problem 14, Page 183) There are 200 graduate students, out of which 110
female and 125 outofstate. Of the 110 female students 70 are outofstate.
—
If one student is selected at random what is the probability that the student
is a male?
P
(
male
)=1
−
P
(
female
)=1
−
110
/
200
.
—
If one student is selected at random what is the probability that the student
is outofstate given that it’s a female?
P
(
outofstate

female
)=70
/
110
.
—
Are the events "female" and "outofstate" independent?
P
(
outofstate
) = 125
/
200
6
=
P
(
outofstate

female
)=70
/
110
.
Not
independent.
—
Are they mutually exclusive? No, they can occur together.
•
(Problem 19, Page 183) The probability that a randomly selected student from
a college is female is .55 and that a student works for more than 10 hours per
week is .62. If these two events are independent,
f
nd the probability that a
randomly selected student is
—
Ma
leandwo
rksfo
rmo
rethat10hoursperweek
.
By independence,
P
(
MandW
)=
P
(
M
)
·
P
(
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This note was uploaded on 03/10/2008 for the course ECON 41 taught by Professor Guggenberger during the Spring '07 term at UCLA.
 Spring '07
 Guggenberger

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