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)'.
Use of Weighted Average Formula. The concept of weighted average is used in various financial formulas. Weighted average cost of capital (WACC) and weighted average beta are two examples that use this formula. Another example of using the weighted average formula is when a company has a wide fluctuation in sales, perhaps due to producing a seasonal product.