1, a product from 34 yuan, bought 10, a product from 45 yuan, bought 20. What is the average price of products A and B?

At this time, the arithmetic average must not be used, directly (34+45)/2, because the quantity they bought is different, so to calculate their average price, they can only use the quantity they bought as the weight for weighted average:

(34×10+45× 20)/(10+20) =1240/30 = 41.33 yuan/piece.

The concept of weight

Weight is a relative concept, aiming at an indicator. The weight of indicators refers to their relative importance in the overall evaluation. Weight refers to the quantitative distribution of the importance of different aspects of the evaluated object in the evaluation process, and the role of each evaluation factor in the overall evaluation is treated differently. In fact, an evaluation without focus is not an objective evaluation.