Standard DeviationWhat?
posted by bart on .
I cannot figure out how to do standard deviation. standard deviation 2, 5, 47, 11, 13, 48, 39, 36

225.125=23.125 = 534.77
525.125=20.125 = 405.02
4725.125=21.875 = 478.52
1125.125=14.125 = 199.52
1325.125=12.125 = 147.02
4825.125=22.875 = 523.27
3925.125=13.875 = 192.52
3625.125=10.875 = 118.27
Sum 2598.41
If I divide by one less,which I am supposed to do I think, I get 371.20 sqrt= 19.27
If I divide by 8 I get 324.80 sqrt=18.02
The possible answers are: A) 24.5 B) 324.9 C) 18 D) 25.1 
I checked all your calculations and found no errors.
(although you wrote your solutions with incorrect use of the "equal' sign)
Here is a webpage, by Wolfram a dependable source,
which explains the difference in the two methods of finding standard deviation.
Check with your text or your instructor whether you divide by N or N1 .
I also got 19.27 after dividing by 7 and
18.02 after dividing by 8, so I don't know where they get your answers. 
oops
forgot to post the webpage.
http://mathworld.wolfram.com/StandardDeviation.html