PROBABILITY
STAT/MA 416 sections 041 and 162 , SPRING 2013
"By chance, or nature's changing course untrimmed"
William Shakespeare- Sonnet 18
Instructor: Dr. Jeana
Alice Vatamanelu
Office: MATH 750
Phone: 765 494 1497
Email:
jvataman@math.purdue.edu
Courses numbers: 60992 and respectively 66716
Classes: MWF, 11:30 am-12:20 pm, in UNIV 117, and respectively 10:30 am-11.20 am,
in UNIV 001
Office hours: MW, 12:30
pm-1:30 pm
Books:
1. Introduction to probability, by George Roussas (mandatory)
2. A first course
in probability, by Sheldon Ross, 8th edition (optional)
3. A
introduction to probability and its applications, by
William Feller (optional)
4. Fundamentals of probability: A first course, by
Anirban Dasgupta (optional)
Other
sources:
(free
pdf) Mathematics for computer science (from Chapter
18-Introduction to probability, to Chapter 25-Random
Walks), by Eric Lehman and Tom Leighton. Highly
recommended.
Lecture
Notes 2013
Lecture
Notes 2012
Homeworks
Quiz 2+Solutions
Course
description
INFORMATION ABOUT THE FINAL
Prepare:
Independence of 2 events, independence of 3 events,
pairwise independence of 3 events, relations among them.
Properties of probability, be prepared to apply them in
exercises.
Trees and conditional probability, The Product rule, The
Total probability formula, Bayes Formula.
How to find F given f, and viceversa, in the continuous
1-dimensional and 2-dimensional cases.
The definition and properties of the distribution
function F in the 1-dimensional case.
The definition of the density in both continuous and
discrete case. How to find c s.t. f is a density.
The analysis of each type of discrete and continuous
random variables. From the discrete ones put the accent
on Poisson. From the continuous ones put the accent on
the Exponential and the Normal.
The connection between the Poisson and the Exponential
(with proof). The memorylessness property of the
Exponential. All types of exercises cocerning the
Exponential.
The reduction of an arbitrary Normal to the Standard
Normal (with proof). All kind of proofs and exercises
that require changes of variables involving the Gaussian
integral. The value of the Gaussian integral. Exercises
using the reduction to the Standard Normal.
The properties of the Gamma function, the definition of
the Gamma function. Computations involving changes of
variables bringing an integral to the integral from the
definition of the Gamma function. The relation between
the Gamma function and the Gaussian integral.
Exercises with the Uniform continuous distribution. The
probability that a U[a, b] r.v. takes values in a
subinterval of [a, b].
Joint density, marginal and conditional densities, etc.,
all step by step construction leading to the conditional
expectation and variance. To carry on all steps of this
construction starting from the joint density in both
discrete and continuous case.
Properties of conditional expectation, especially the
Crucial one. The formula of Total Variance (with ptoof).
To know how to apply in exercises the Crucial property
of Conditional expectation (like in the problem with the
miner). This is the most important chapter.
Independence. Definition, criteria, necessary
conditions, proofs, exercises in which we use
independence or in which we deduce independence. Accent
on criteria 3 and 4. Connection with the m.g.f.
To apply in exercises CLT.
INFORMATION ABOUT MIDTERM 2
Prepare
1)The Hypergeometric distribution.
2)The Uniform distribution both in discrete
and continuos case, the differences between
the discrete and continuos case like reflected
in ex. 2 from Sample Midterm 2, 2010.
Exercises similar to those in the lecture
notes for the Uniform continuos distribution.
3)The relation between the Poisson
distribution and the Exponential one, like
reflected in ex. 4 and 6 from Sample Midtm. 2,
2010. How to prove that the waiting time
between 2 Poisson occurrances is an
Exponential. How to prove Memorylessness and
how to apply it.
How to prove that if X is an Exponential, then
cX is also an Exponential. How to prove that
if X is an Exponential>c, then X-c is an
Exponential. How to use that for a Poisson
r.v. the parameter is proportional to the
length of the subinterval.
4)To use the Var(X) for finding the
expectation of X^2. To use the derivatives of
the M.g.f. for finding the moments of X.
5)To know the definition of the Gamma function
and its properties, to do changes of variables
that take you from another integral to the
integral in the definition of the Gamma
function. The relation between the Gamma
function and the Gaussian integral, as in the
last ex. from Lecture notes 17. The relation
between the Gamma distribution and the
Exponential one.
6)To use that if X and Y have the same
distribution, then P(X>Y)=1/2. To use that
if X is a continuos r.v., then P(X=a)=0 for
any real a.
7)To use trees where the conditional
probabilities on some branches have to be
computed with random variables, like in
problems 8 or 9 from the Sample Midtm. 2,
2010.
8)To solve exercises with the Normal using the
property that if X~N(a, b^2), then (X-a)/b is
a Standard Normal. To do changes of variables
that bring an integral to the Gaussian
integral. To prove the Crucial Remark from the
lesson with the Normal.