AQA Statistics 1 6.04 Estimation and finding a 90% Confidence Interval

[taslimtorabally]

Hi Jack - This is a great video. Very helpful indeed.

[mohammaddawodieh]

we did use the estimated standard error of the sample mean as S/sqrt(n) ; because we don't know the population mean and the population variance right?

[louismcelgunn]

I don't understand why in the standard error the standard deviation is also square rooted? is it because we are given the variance and not the st deviation, so square root o variance = standard

[fstnukezz]

How to know if it is unbiased variance or just varianc e.g ( sigma (x-meanx)^2/n)

[mohammaddawodieh]

Can we consider this case as a t-distribution and do the test; since the sample size is greater than 30 and the population variance is unknown?