Statistics 104 – Spring 2011
Section #3
Topics for Section
Probability and Conditional Probability
Unions, Intersections, Complements, Disjoint Events
2 x 2 Tables
Independence of Events
Bayes' Rule/Theorem
Practice Problems
1. Kevin has a tomato garden which at times needs watering. On any given day, when it rains, Kevin
will water his plants with probability zero (we don't need to water on rainy days). When it does not
rain, Kevin waters his plants with probability 0.8. There is a 25% chance overall that it rains on any
given day in the summer. We define the two events
R
: rains on any given day in the summer
W
: Kevin waters his plants on any given day in the summer
a. Are the events
R
and
W
disjoint? Justify both by an intuitive argument and by explicit calculation.
b. Are the events
R
and
W
independent? Justify both by an intuitive argument and by explicit
calculation.
c. Are the events
W
and
R
independent? Justify both by an intuitive argument and by explicit
calculation.
d. Given that Kevin did not water his plants on a particular day in the summer, what is the probability
that it was actually a rainy day?
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
2. When police set up sobriety checkpoints to check for drunks, drivers are stopped and asked a few
brief questions. Based on the answers, the police officer judges whether the driver has been drinking. If
the officer does not think that the driver has been drinking, he or she is released without a breath test.
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '11
 MichaelParzen
 Statistics, Conditional Probability, Probability, Probability theory, Type I and type II errors, Probability space

Click to edit the document details