Department of Economics
Professor Dale J. Poirier
University of California, Irvine
October 23, 2001
MIDTERM
TEST
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.
1.
Suppose your neighbor has two children. Assume that the gender of a child is a Bernoulli
random variable with
θ
= ½
and that gender is independent across births.
(10)
(a)
Suppose you ask her whether she has any boys, and she says yes. What is the
probability that the other child is a girl?
(10)
(b)
Suppose instead that you happen to see one of her children run by, and it is a boy.
What is the probability that the other child is a girl?
(25)
2.
A miner is trapped in a mine containing three indistinguishable doors.
The first door
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 Fall '10
 DaleJ.POIRIER
 Econometrics, Variance, Probability theory, Cumulative distribution function, Bernoulli random variable, Dale J. Poirier

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