# Calculating standard deviation

Printable View

• Apr 28th 2013, 08:31 PM
pmishra
Calculating standard deviation
Hi, Given sample size as 25 and mean as 56, can any one of you help me calculating standard deviation?(Thinking)
• Apr 28th 2013, 10:46 PM
chiro
Re: Calculating standard deviation
Hey pmishra.

You need to have information about the sample. If you have the sample just add up the sums of squares (i.e. (x_i - mean)^2) for every i from 1 to 25 and divide that total answer by n - 1 (n = 25) in your case.
• Apr 30th 2013, 03:58 AM
ibdutt
Re: Calculating standard deviation
Remember that standard deviation is also called root mean square deviation. That means square root of the mean of the squares of deviation.
• May 9th 2013, 09:05 PM
sarovaganam
Re: Calculating standard deviation
The standard deviation of returns is important to investors because it is the standard measure of investment risk, and investment risk is the degree of uncertainty of earning the expected rate of return. As you will see, the standard deviation of returns can be used to estimate the probability of the return on an investment falling within a given range relative to the expected rate of return in any given period.

maths tutor | statistics tutor
• May 10th 2013, 05:48 AM
HallsofIvy
Re: Calculating standard deviation
Quote:

Originally Posted by pmishra
Hi, Given sample size as 25 and mean as 56, can any one of you help me calculating standard deviation?(Thinking)

No. Given any $\displaystyle \sigma> 0$ you can construct a sample, of size 25 and mean 56, having that standard deviation.