The arithmetic mean is a single value meant to sum up a data set. All that formula is saying is add up all of the numbers in your data set S means add up and x. Use the mean to find the variance.
In is a random variable with its own distribution called the sampling distribution.
N 10 Xx85 b. X 1 x N the sample data set. N 18 Ex x 248 a. Calculate the mean for samples for which the sample size and Ex x are given below.