Fn key. Not to be confused with Function key. The Fn key, short form for function, is a modifier key on many keyboards, especially on laptops, used in a compact layout to combine keys which are usually kept separate. It is typically found on laptops due to their keyboard size restrictions.
For a finite set of numbers, the standard deviation is found by taking the square root of the average of the squared deviations of the values from their average value. For example, the marks of a class of eight students (that is, a population) are the following eight values:
For the set of test scores, the standard deviation is the square root of 75.76, or 8.7. Remember that standard deviation needs to be interpreted within the context of the data set. If you have 100 items in a data set and the standard deviation is 20, there is a relatively large spread of values away from the mean.