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 Method Overview. The weighted average method is used to assign the average cost of production to a product. Weighted average costing is commonly used in situations where: 1  Inventory items are so intermingled that it is impossible to assign a specific cost to an individual unit.hen using the weighted average method, divide the cost of goods available for sale by the number of units available for sale, which yields the weighted-average cost per unit.