Three sell orders are placed for a stock today. Listed below are the bid and ask quotes at various times: The following trades take place: a. At 10:00 AM, the trader placed an order to sell 100 shares. The execution price was $12.11. b. At 1:00 PM, the trader placed an order to sell 300 shares. The execution price was $12.00. c. At 2:00 PM, the trader placed an order to sell 600 shares. The average execution price was $11.75. Calculate the quoted and effective spreads for each of these orders. Calculate the average quoted and average effective spread