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my girlfriend is taking a business statistics class and she had a test today. she got stumped on a question and wrote it down so she could ask me about it when she got back since I'm pretty good at math. I tried solving it but from what i can tell it seems like you would need to know the mean in order to find the variance. the question is below:

Find the Variance:

n = 5

[tex]\Sigma x^{2}[/tex] = 1320

[tex]\Sigma[/tex]x = 80

I expanded out the variance formula. since we run from i=1 to n (where n=5)

I got the formula V = 1320 - 160[tex]u^{2}[/tex] + 5[tex]u^{2}[/tex][tex]/5[/tex]

where u = the mean.

My girlfriend says that the mean was not specified in the problem. I would have given my answer for the variance as a function of the mean as you can see above, but since this is a business statistics class i have the tendency to believe the teacher is expecting a numerical answer. Does anyone have any insight into how this problem can be solved, or is there not enough information given?

Thank you.

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# Finding variance without knowing mean?

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