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FINAL EXAM
PSTAT 5E
HSU
12/12/00
Name
Signature
1. I have two cats, Ray and Felix, who behave independently of one another. I know that at
4:00 pm there is a 0.3 chance that Ray will be in my garage and 0.9 chance that Felix will be
in my garage.
(a) If I walk into my garage some day at 4:00 pm, what is the probability that both cats
will be in the garage?
(b) If I walk into my garage some day at 4:00 pm, what is the probability that at most one
cat will be there?
(c) Consider the random variable X which represents the number of cats I ﬁnd in my garage
at 4:00 pm. Find the probability distribution of X.
(d) Calculate the expected value and variance of
X
in (c).
1
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View Full Document2. Of the freshmen in a certain college, it is known that 40% attended private secondary schools
and the remainder attended public schools. The registrar reports that 30% of all students
who attended private secondary schools but only 20% of those who attended public schools
attain A averages in their freshman year. At the end of the year, one student is chosen at
random from the freshman class.
(a) What is the probability that he attended a public school and attains an A average in
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 Spring '08
 LANDRIGAN

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