A. Based on the tutorial on Product Remanufacturing, Recovery and Reconfiguration, answer the following short questions:

Evaluating the product reuse performance in 5 steel companies (x1, x2, x3, x4, x5). According to main steelmaking by-products and their reuse in the case study, product reuse can be presented through the following 4 attributes: the amount of slag to be reused(y1), the amount of dust to be reused(y2), the amount of process gases to be reused(y3), and the amount of other by-products to be wasted(y4).

The weight of each attribute is represented as w={0.2,0.3 0.4 0.1}, and the standardized data is presented in Table 1.

Can you rank the product reuse performance of these five companies by using the TOPSIS?

Table 1. The standardized data of 5 steel companies

j

i	z1(y1)	z2(y2)	z3(y3)	z4(y4)
1	0.0346	0.6666	0.6956	0.6482
2	0.0693	0.5555	0.5565	0.3034
3	0.2078	0.2222	0.1753	0.4137
4	0.1039	0.4444	0.4174	0.5378
5	0.9695	0.0000	0.0398	0.1655

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