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)'.
Weighted average formula is similar to mean formula for frequency distribution, where frequencies can be thought of as weights.The steps used for computing the weighted average are similar to those used in computation of arithmetic mean for frequency distributions.eighted average formula is similar to mean formula for frequency distribution, where frequencies can be thought of as weights.