Binomial and Normal Distribution

Date: 06/09/99 at 03:52:52
From: Emma 
Subject: Normal distribution

Could you please tell me the difference between normal approximation 
to binomial distibution and normal distribution?

Date: 06/09/99 at 05:47:24
From: Doctor Mitteldorf
Subject: Re: Normal distribution

The binomial distribution is really a bar graph. It's the probability 
of getting r heads when you flip a coin n times, and r is an integer 
between 0 and n, so it's n+1 bars all together.

But as n gets bigger and you step back and look at the bar graph, it 
looks smoother and smoother, with smaller and smaller bars closer and 
closer together. It begins to take on the shape of a normal 
distribution, which is a smooth, continuous curve. The normal 
distribution it looks like has a particular mean and standard 
deviation; those two numbers together completely describe any normal 
distribution.

A normal distribution that is "fitted" in this way to be as close as 
possible to a particular binomial distribution is called a "normal 
approximation to the binomial distribution."

- Doctor Mitteldorf, The Math Forum
  http://mathforum.org/dr.math/