With penalties and minimum withdrawal requirements to consider, timing is of the utmost importance when taking money from your IRA. (Getty Images) Individual retirement accounts, commonly known as IRAs, are retirement fund staples for many people.
In statistics, the mean is the mathematical average of a set of numbers. The average is calculated by adding up two or more scores and dividing the total by the number of scores. Consider the following number set: 2, 4, 6, 9, 12. The average is calculated in the following manner: 2 + 4 + 6 + 9 + 12 = 33 / 5 = 6.6.
For example, suppose your data is all of the ACT scores of the students in a small class. Then the standard deviation formula is Suppose the scores are 15, 21, 21, 21, 25, 30, and 35. The mean of this set is 24.8, 88, 67, 90, 92, 83, 97. The highest test score is 97 and the lowest is 67, therefore the range is 97-67 = 30. The standard deviation is another way to measure how close together the elements are in a set of data. The s.d. is the average distance between each data point and the mean.