A popular mobile company is planning to introduce a new mobile in the market. Previously they have worked with three different suppliers dealing in improved high-resolution screen. Prices offered by all these suppliers are as follows; Supplier A: $4.20 per unit. Supplier B: $3.60 per unit (If order size (Q) ) Supplier C: $3.20 per unit, (If order size (Q) 4,500)

Annual demand for this new mobile is estimated to be 20,000 units. The order setup cost is $150 independent of the selected supplier. If the interest rate to be considered in holding costs is 16% annually, answer the following

a) Which source should be used, and what is the size of the order?

b) What is the optimal value of holding and setup costs for subassemblies when the optimal source is used?