### Math 225 Course Notes

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### Chapter 4

#### Contents

The possible values of
discrete random variables can be listed.
The sum of the probabilities of these possible values is one.
The binomial distribution,
the random variable that comes from counting heads while flipping coins,
is the most useful discrete random variable
and is a model for random sampling from a population
with two types of individuals.
The distribution of a continuous random variable
is described by its
probability density function.
Probabilities correspond to areas under the curve.
The normal distribution is the most important example
of a continuous random variable.
This is the distribution of the mean from moderate to large random samples,
and also the distribution of random variables
in many other examples.

Last modified: Jan 22, 1996

Bret Larget,
larget@mathcs.duq.edu