The standard deviation is a measure that indicates the extent to which the peaks and troughs of a wave differ on average from the mean voltage. A large standard deviation is a measure of large amplitude waves, i.e., on average the peaks and troughs differ by a large extent from the mean voltage.
The weighted average formula is used to calculate the average value of a particular set of numbers with different levels of relevance. The relevance of each number is called its weight. The weights should be represented as a percentage of the total relevancy. Therefore, all weights should be equal to 100%, or 1.
Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).