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sequence, one ball is chose at random from each bin. What is the probability that the
sequence 9-1-1 would be the one selected on any particular day
4. On August 8, 2011, the Dow Jones Industrial fell 635 points (5.5%) to 10,810 points,
representing the 6 th worst point loss ever experienced. On that day, President Obama‟s
approval ratings also suffered tremendously; only 22% of the nation‟s voters “Strongly
Approve” of how he is performing in the presidential role (SOURCE:
http://www.rasmussenreports.com/public_content/politics/obama_administration/daily_pr
esidential_tracking_poll).
Suppose presidential hopeful Randall Terry (Democrat) speaks at a rally shortly
thereafter and assumes that his approval rating as a candidate will likely closely mirror
President Obama‟s. Suppose there are 40 swing voters (voters that are “on the fence”
about who to vote for). (Video Solution)
a. What is the probability that all 40 voters will strongly approve of Terry‟s plan
b. What is the probability that none of the 40 voters will strongly approve of Terry‟s
plan
c. What is the probability that at least one voter will approve of Terry‟s plan
5. The following case study is reported in the article "Parking Tickets and Missing
Women," which appears in an early edition of the book Statistics: A Guide to the
Unknown. In a Swedish trial on a charge of overtime parking, a police officer testified
that he had noted the position of the two air valves on the tires of a parked car: To the
closest hour, one valve was at the 1 o' clock position and the other was at the 6 o' clock
position. After the allowable time for parking in that zone had passed, the policeman
returned, noted the valves were in the same position, and ticketed the car. The owner of
the car claimed that he had left the parking place in time and had returned later. The
values just happened by chance to be in the same positions. An "expert" witness
computed the probability of this occurring as (1/12)(1/12) = 1/144.
a. What reasoning did the expert use to arrive at the probability of 1/144
b. Can you spot the error(s) in the reasoning that leads to the stated probability of
1/144 What effect does this error(s) have on the probability of occurrence Do
you think that 1/144 is larger or smaller that the correct probability of occurrence
6. Jeanie is a bit forgetful, and if she doesn't make a "to do" list, the probability that she
forgets something she is supposed to do is .1. Tomorrow she intends to run three errands,
and she fails to write them on her list.
a. What is the probability that Jeanie forgets all three errands What assumptions did
you make to calculate this probability
b. What is the probability that Jeanie remembers at least one of the three errands
c. What is the probability that Jeanie remembers the first errand but not the second
or third
7. One of the myths most commonly believed by students on multiple choice exams is that,
as long as they always use letter „C‟ as their guess, they increase their chances of
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