Castle Co. needs to borrow $10 million for process improvement upgrades. Management decides to sell 20-year bonds. They determine that the 3-month Treasury bill rate is 2.75 percent, the firm's credit rating is A, and the yield on 20-year Treasury bonds is 1.80 percent higher than that for 3-month Treasury bills. Bonds with an A rating are selling for 50 basis points above the 20-year Treasury bond rate. What is the borrowing cost for this transaction?