Central limit theorem Imagine that you are doing an exhaustive study on the children in all of the elementary schools in your school district. You are particularly interested in how much time children spend doing active play on weekends. You find that for this population of 2,431 children, the average number of minutes spent doing active play on weekends is μ = 87.85, with a standard deviation of σ = 118.1. You select a random sample of 25 children of elementary school age in this same school district. In this sample, you find that the average number of minutes the children spend doing active play on weekends is M = 79.07, with a standard deviation of s = 129.91.

The difference between M and 1.1 is due to the :_______