Suppose σ=36 and sample size n = 81. what is the standard error (s. e) of x ̅?

The standard error of the mean is labelled as: σM. The formula for the standard error is: where σ is the standard deviation of the original distribution and n is the sample size. The formula is σ / square root n

So the given in our problem is:

σ=36

n = 81

Standard Error = 36 / sqrt81

= 36 / 9

= 4