Question

data from sample of 400 cases, variable has 95% confidence interval of 54.3 to 54.7
I found the mean-
how do i find standard error- step by step please.


Standard error = sd/√n

Note: sd = standard deviation; n = sample size.

You'll need to determine the standard deviation in order to find the standard error.

I'm assuming you determined the mean to be 54.5; therefore, you can determine standard deviation using the following method.

.2 = 1.96 (sd/√400) -->.2 represents the margin of error.

Solve for standard deviation, then you will be able to determine the standard error.

I hope this will help.