STAT4101
Practice Exam 1
October 5, 2007
The exam is closedbook, but you may bring one sheet of lettersized paper with notes on
both sides. You will need a calculator.
1. In the recent
Minnesota Poll
conducted by the Star Tribune newspaper and reported
on October 3, only 30% of Minnesotans approve of the way George W. Bush is handling
his job as president.
(The remaining 70% either disapprove, don’t know, or refused
to answer.) Broken down by party affiliation, 5% of Democrats, 70% of Republicans,
and 25% of Independents approve. (Independents include everyone who is not either
a Democrat or a Republican.)
(a) Assuming 40% of Minnesotans are Independents (in 2004 it was 38%), show that
33.8% of Minnesotans are Democrats and 26.2% are Republicans.
(b) You meet a Minnesotan who approves of Bush. Using the result in part a, what
is the probability that this person is a Democrat? (Assume you met this person
randomly.)
2. Consider two events:
A
and
B
. We know that
P
(
A
) = 0
.
6 and
P
(
B
) = 0
.
5.
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 Fall '10
 Any
 Statistics, Probability, Star Tribune newspaper, recent Minnesota Poll

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