Some purchasing specialist jobs also assign specialists to track the maintenance of office equipment. Maintaining records of warranties and service agreements is sometimes expected of a person in this position.
A retail price index would take this into account and use a weighted average which gives more prominence to commonly bought items. Excel does not contain a built in function to calculate a weighted average. It is however easy to do it using the SUMPRODUCT() function in a simple formula. SumProduct() multiplies two arrays (or ranges) together and returns the sum of the product. In the illustration it would calculate '(B4 x C4) + (B5 x C5) + (B6 x C6)'.
Stockbyte/Stockbyte/Getty Images. The weighted average is the mean of a set of numbers in which some numbers are worth more, or carry more weight, than others. Knowing how to calculate weighted average is beneficial when calculating grades, since different assignments, exams and quizzes often carry different weights.1  How to Do a Weighted Score. 2  How to Calculate Weighted Average.he weighted average is the mean of a set of numbers in which some numbers are worth more, or carry more weight, than others. Knowing how to calculate weighted average is beneficial when calculating grades, since different assignments, exams and quizzes often carry different weights.