Finding the mean of a population is a way to analyze information to find the average of a set of numbers that encompasses the entirety of a group. As opposed to taking a sample and estimating the mean of the whole, population mean gives a more accurate answer.
Make a list of numbers, one for each member of the population. In this example, calculate the mean age in a population of 10 children. The list of their ages might look like this: 9, 5, 10, 4, 9, 9, 3, 2, 12, 7.
Add the numbers. In the example, 9+5+10+4+9+9+3+2+12+7= 70.
Divide the answer from Step 2 by the total number in the population, in this case 10. In the example, 70 divided by 10 equals 7. The mean age for the 10 children in the example population is 7.