Question 4 (Total 20 marks). XYZ Co. Ltd. is a Hong Kong based company and they have their own factory in Shenzhen, China. They have two suppliers A & B. XYZ management has identified three performance dimensions for supplier evaluation: cost, quality and on-time production. XYZ management has established importance weights of 0.2, 0.5 and 0.3 for cost, quality, and on-time production, respectively. You, as an operation manager at XYZ have rated the performance of suppliers A and B with regard to these three dimensions. Their ratings (1=poor to 5=excellent) are as follows: Performance ratings Performance dimension Supplier A Supplier B Cost 5 3 Quality 5 On-time production 3 5 a) Use the weighted-point evaluation system to calculate the weighted average performance for suppliers A and B and determine the best supplier based on the total score of performance. (4 marks) b) XYZ Co. Ltd can buy 80,000 units of accessories from either supplier A or supplier B. From supplier A, accessories are shipped by rail, taking 16 days at a cost of $1,600. While from supplier B, it takes 4 days at a cost of $3,500 by truck. The accessories' holding cost per unit per year is $0.25 and holding cost will be incurred during the delivery. Assume 250 working days per year. Calculate the total cost of buying the accessories from suppliers A and B respectively and determine the best supplier based on the total cost. (Hints: calculate the daily holding cost first - Show your calculation steps) (4 marks)