- Thread starter JWade
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My homework problem says:

For the following summary statistics, find ∑X and SS (sum of squares)

a. XBar = 25, s = 10, n = 11

So, I think that ∑X = 225 but am having trouble how to find SS. Thanks in advance for any help!

For the following summary statistics, find ∑X and SS (sum of squares)

a. XBar = 25, s = 10, n = 11

So, I think that ∑X = 225 but am having trouble how to find SS. Thanks in advance for any help!

In my notes I have that XBar = ∑X/N .. so I did 25 = ∑X/11 .. 25 x 11 = 225

Is that not right?

Is that not right?

for the second question here's a small hint. you have the standard deviation. from the standard deviation you can get the variance, right? and if you had real data and not the standard deviation, how is it that you calculate the variance? what would the formula be?

10^2 = (275 - 25)^2 / 10 ... What am I doing wrong? Clearly there's not a variable to solve for. I just don't understand what I am supposed to be doing I guess... the only thing I have written in my notes for SS is Sum of Squares/Degrees of Freedom ... and I can't find much help online as to what SS even is. I feel stumped.

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.

That said, the Variance for your variable X is equal to:

I hope this helps.

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If all of you understand I don't get why you can't help me.

(Suppose I said that the answer is 42. Would that really help you?)

I just want to understand...

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.

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!

That said, the Variance for your variable X is equal to:

I hope this helps.

So.. x=1000...?