Business Statistics What do i do with the Σ in this sample varaiance formula?

I am trying to find the sample variance and standard deviation. I have already found the sample mean which is 0.567196262. Now I have tried the following formula for sample variance





Σ(Xi - X¯ )^2 / N – 1





Where n = 963


Xi = 546.21


X¯ = 0.567196262


Note: the line should have been over the x and not to the right of it.





What I get is 309.4865585


I am not sure what to do with the Σ


What am I missing?

Business Statistics What do i do with the Σ in this sample varaiance formula?
you are using the least squares method..This will take all day





That symbol Σ


means "sum of" so you have to take each data point (all 963) subtract the mean and then divide by 962 and then add all of those answers!





your "xi" is incorrect ..it means every data point shown individually.. that 546.21 is just one of the 963 total ones..Don't do this by hand it will take all day
Reply:The sample varairance formula is correct.





But there shoud be a statistic sample avalible. X1,X2, X3,X4......X963. Each one with the real value.





The calculation is,


[(X1-X¯ )+(X2-X¯ )+......+(X963-X¯)]/(963-1)





I think you can use the EXCEL to calculate it.