# Thread: Sum of Squares help!

1. ## Re: Sum of Squares help!

Well, take a deep breath - you have the Summation(X) correct: 275=(n)*(XBar), Mkay.

That said, the Variance for your variable X is equal to: Variance(X) = SS(X)/(n-1), where (n-1) is your degrees of freedom. You are given the standard deviation for your variable X i.e., s=10. So what is the relationship between the variance of X and the standard deviation of X? Once you have that, you can solve for the SS(X).

I hope this helps.

2. ## Re: Sum of Squares help!

If all of you understand I don't get why you can't help me.
(Haven't you noticed that we are trying to help you all the time?)

I just want to understand...

3. ## Re: Sum of Squares help!

YMade an account hoping to get some help with it. Now I just feel like an idiot since the problem is apparently so simple and I just am missing something. If all of you understand I don't get why you can't help me. Oh well.
Forum rules [agreed to, when creating each account] disallow solving homework problems by giving whole answers. An easy answer might be unethical and sometimes problematic, as it interferes with the process of learning and even might be considered cheating.
Otherwise, it would be much easier for most of forum contributors to simply write the complete solution and leave to the next thread, instead of patiently trying to highlight the problem through asking questions and giving hints.

On another note, it is pretty natural to put 2 days on a statistics/math problem. I for one have put months on some of my problems to no avail!

4. ## Re: Sum of Squares help!

Originally Posted by Dragan
Well, take a deep breath - you have the Summation(X) correct: 275=(n)*(XBar), Mkay.

That said, the Variance for your variable X is equal to: Variance(X) = SS(X)/(n-1), where (n-1) is your degrees of freedom. You are given the standard deviation for your variable X i.e., s=10. So what is the relationship between the variance of X and the standard deviation of X? Once you have that, you can solve for the SS(X).

I hope this helps.
So, the standard deviation is the square root of the variance. So, that would mean if the standard deviation is 10, the variance is 100?

So.. x=1000...?

5. ## Re: Sum of Squares help!

Well, yes, basically you're correct. In more detail, it would be the Sums of Squares associated with the variable X, which is 1000. Note, that this is what I perceived from the very beginning, which is based on your query in your original post, JWade.

6. ## Re: Sum of Squares help!

So at this point, I just use the formula for s^2 that I posted before, and that is SS?

7. ## Re: Sum of Squares help!

Yes that is correct - well no, you're right. :-)

In short, yes, that is what you should do. And, after much consternation and with some hope, this will end this discussion.

8. ## Re: Sum of Squares help!

Sorry.. Thank you for your help.

9. ## Re: Sum of Squares help!

Hey no need to be sorry. Honestly we're glad you're here and hope you come back.

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