The estimated construction cost of a stadium is $42 million. The owner is authorized to issue $46 million in view of risks and uncertainties. Half of the bonds will be redeemable at the end of 10 years with annual interest at 10% of the bond principal and half of the bonds will be redeemable at the end of 15 years with annual interest at 15% of the bond principal. Banks bid the amounts they are willing to secure payment support. The banks recover their expense and profit by offering to provide a sum of money slightly less than the amount to be repaid. The highest bid received is $44 million. What is the rate of financial cost in issuing the bonds?