TExES Mathematics 4-8 (115) Practice Exam - Prep & Study Guide

The first step in calculating variance is to subtract the mean from each number in the data set. This process is essential because variance measures how far each number in the set deviates from the average. By finding the difference between each data point and the mean, you can determine whether the data points are above or below the average, which is crucial for the subsequent steps.

Once the deviations are calculated, the next steps involve squaring each of these differences to eliminate any negative values and then averaging those squared differences. This sequence of operations allows us to quantify the spread or dispersion of the data, which is precisely what variance represents.

Understanding this foundational step helps clarify the reasoning behind the calculations that follow, leading to a comprehensive grasp of how variance is determined.