Answer:
And replacing we got:
And then the estimator for the standard error is given by:
Step-by-step explanation:
For this case we have the following dataset given:
20.05, 20.56, 20.72, and 20.43
We can assume that the distribution for the sample mean is given by:
And the standard error for this case would be:
And we can estimate the deviation with the sample deviation:
And replacing we got:
And then the estimator for the standard error is given by: