Department of Economics
Professor Dale J. Poirier
University of California, Irvine
October 31, 2006
MIDTERM EXAM
ECON 220A
Statistics and Econometrics I
(open book)
Directions
: You must answer each of the following questions.
Points (out of 100) are allocated
as noted to the left of each question.
Allocate your time according to these points.
To receive any
partial credit, you
must
show your work.
Results from the text need not be reproduced in detail -
you can merely cite the source.
(20)
1.
A population of voters contains 40% Republicans and 60% Democrats. It is reported
that 30% of the Republicans and 70% of the Democrats favor an election issue. A
person chosen at random from this population is interviewed and found to favor the
issue in question. Find the probability that this person is a Democrat.
(20)
2.
Let Y be an integer-valued random variable for which P(Y = i) = p

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