MATH 140 Lecture Notes - Lecture 2: Interquartile Range, Shamash, Standard Deviation
Document Summary
During today"s lesson, professor shamash explained to us the relationship of mean and standard deviation. If a distribution is bell-shaped, it is considered a normal distribution. Meaning, the mean (or the balancing point) & standard deviation completely reflect the distribution itself. The focus of the lesson was to understand the steps on how to calculate standard deviation. 49 + 50 + 51 =150 150/3 = 50 mean = 50: x(bar) = 150/3 = 50, (x-x[bar]) Total of 0: ( x - [sigma]) ^2 (-1)^2 = 1 (0)^2 = 0 (1)^2 = 1. Depends on what we are comparing it to. Today"s lesson was based on the empirical rule. The empirical rule helps us understand how the standard deviation measures variability in a problem. Usually all rules will be within 3 standard deviations of the mean. If it is unimodal and symmetric, the measurements are: 68% one standard deviation away from the mean.
