# Find the Standard deviation

• Jul 2nd 2011, 05:42 PM
RedonYellow
Find the Standard deviation
I am given a table of values here.

http://i233.photobucket.com/albums/e...han7/dm2-1.jpg

When I put them into my calculator, it gives me a standard deviation of 4.40. However, the example says to assume that it is 3.50. This makes no sense to me. The problem only gives the table of numbers, so I don't see why I should assume that the standard deviation is 3.50. Do you understand how they are calculating the standard deviation?
• Jul 2nd 2011, 06:32 PM
TKHunny
Re: Find the Standard deviation
It is assumed, not calculated. You do not know if this table is a good representation of the entire population unless it is stated in the problem description. Do not assume that it is useful for calculating the variance unless you believe it is useful for that. The problem statement seems to be suggesting that it is not useful for that and that you should assume the standard deviation is 3.50.
• Jul 2nd 2011, 06:40 PM
RedonYellow
Re: Find the Standard deviation
This is the example problem. When I solve the actual problem, I keep getting it wrong because I'm not assuming what the standard deviation is correctly. The assumed variance varies from problem to problem. It doesn't make any sense to me. I don't understand how I'm supposed to find the number.
• Jul 2nd 2011, 07:01 PM
TKHunny
Re: Find the Standard deviation
Quote:

Originally Posted by RedonYellow
I'm not assuming what the standard deviation is correctly.

Well, stop it. If the problem says the standard deviation is "tapioca", then that it what it is. Of course, that's a bit intractable, but that's what it is. If the problem statement says "assume" and you try to "calculate", then you made an error.

Post an actual problem and let's see your work.
• Jul 2nd 2011, 07:13 PM
RedonYellow
Re: Find the Standard deviation
Sorry, It was my fault I couldn't figure it out. I missed a spot in the directions, and after I saw it, I was able to figure it out. Thank you TKHunny for your help.