Standard Deviation

[tanyuj]

Ok
Statistics 1/S1 Heinemann's textbook

Pg 99
Q10. Find the Stardard deviation of the following set of numbers:
13, 17, 8, 17, 12, 6, 11, 11, 10, 5.

Im not sure how to approach this question

But I know I may have to apply the Formula being

√∑x/n - (∑x/n)

the answer is 3.85..
Im not sure how to get it...

Thanks in advanced

[Delta]

All your numbers represent x

just do √ (13 + 17 + ....+ 5) -[(13+17+...+5)/10]

[tanyuj]

ok I think I got it...I wasn't too sure...went browsing the net how to solve Standard Deviation came across this example...

http://www.bbc.co.uk/scotland/education/bitesize/standard/mathsII/statistics/standard-deviation_rev4.shtml

and started using this formula:

http://www.bbc.co.uk/scotland/education/bitesize/standard/img/mathsII/statistics/standard_deviation1.gif

x | x-x bar | (x -x bar)
13 | 2 | 4
17 | 6 | 36
8 | -3 | 9
17 | 6 | 36
12 | 1 | 1
6 | -5 | 25
11 | 0 | 0
11 | 0 | 0
10 | -1 | 1
5 | -6 | 36

Σ(x -x bar) = 148

SD = 148/10
SD = √14.8
= 3.847
= 3.85

I just want confirmation that I am right...

[KatieB]

This is fine. The other formula given by Delta is generally easier and quicker to do though.