Next divide the sum from step one by the total number of items in the data set. Square each of the differences from the previous step and make a list of the squares. Sample size cannot be back-calculated from only mean and standard deviation.
A given set of data is added and divided by total numbers.
Sometimes sample size is hidden in unexpected places within a manuscript. Divide sum by the number of samples. We can however make some statements about the likely characteristics of a random sample of a given size. Sample mean is calculated by finding the sum of all terms in the selected sample and dividing this figure by the total number of terms.