Demand for phones at Amazon is 5,000 per month. Holding cost is 20 percent and the company incurs a fixed cost of $500 for each order placed. The supplier offers an all unit quantity discount with a price of $200 per phone for 0 to 10,000 phones in an order, a price of $190 for 10,000 - 20,000 phones and a price of $180 for above 20,000. 4.1. (2 points) Calculate On, Q and Or where the slope of the total costs are 0. Q. = Q = 4.2. (2 points) What are the three candidates On$, Q,* and Q* for the optimal order quantity Q*? Q, $=4.3. (2 points) Calculate the total costs at On*, Q* and Q,*. TCO = TC1 = TC = 4.4. (2 point) What are the optimal order quantity Q* and the minimum total cost