1) The document discusses standard deviation and variance as measures of how dispersed data points are from the mean. It provides formulas to calculate population variance, sample variance, population standard deviation, and sample standard deviation. 2) Examples are given to demonstrate calculating variance and standard deviation from raw data sets and frequency distributions. This helps determine which data set or person is more consistent. 3) The empirical rule is described, stating that approximately 68%, 95%, and 99.7% of values in a bell-shaped distribution fall within 1, 2, and 3 standard deviations of the mean, respectively.