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 calculation. The weighted average (x) is equal to the sum of the product of the weight (w i) times the data number (x i) divided by the sum of the weights:ind the weighted average of class grades (with equal weight) 70,70,80,80,80,90: Since the weight of all grades are equal, we can calculate these grades with simple average or we can cound how many times each grade apear and use weighted average. 2Ã70,3Ã80,1Ã90. x = (2Ã70+3Ã80+1Ã90) / (2+3+1) = 470 / 6 = 78.33333.