# standard deviation and mean deviation

• Mar 15th 2008, 01:51 PM
pawan6719
standard deviation and mean deviation
Q::it Is Asked To Show That The Standard Deviation For Normal Distribution Is Approximately 25% More Than The Mean Deviation

I Have Absolutely No Idea As To Proceed
Can I Have A Descriptive Solution
• Mar 16th 2008, 06:09 AM
CaptainBlack
Quote:

Originally Posted by pawan6719
Q::it Is Asked To Show That The Standard Deviation For Normal Distribution Is Approximately 25% More Than The Mean Deviation

I Have Absolutely No Idea As To Proceed
Can I Have A Descriptive Solution

You need to work with the standard normal distribution, and so show that:

$\frac{1}{\sqrt{2\pi}} \int_{-\infty}^{\infty} |x|e^{-x^2/2}~dx \approx 1.25$

RonL