That number 840 is. How does the mean and standard deviation describe data. Pin On Stats CV 01281 100. . At least 3 4 of the measurements will fall within two standard deviations of the mean. If you do not have normal distribution you need to use median and IQR instead. It is possible that very few of the measurements will fall within one standard deviation of the mean Consider a bimodal. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy Safety How YouTube works Test new features Press Copyright Contact us Creators. Subtract the mean x from each value. Mean x 18 20 22 24 26 5 1105. Standard deviation SD is a widely used measurement of variability used in statistics. The Standard Deviation of a set of data describes the amount of variation in the data set by measuring and essentially averaging how much each value in the data set varies from the calculated mean. Low standard...