According to the given information, the 10-year Treasury-bonds yield 3.1% and 10-year corporate bonds yield 7.15%. The maturity risk premium on both 10-year Treasury and corporate bonds is 1.3%, and corporate bonds have a 0.65% liquidity premium while T-bonds have a zero liquidity premium. We need to find the default risk premium on corporate bonds.Part 1: Default risk premium on corporate bondsThe default risk premium is the return on a corporate bond minus the return on a risk-free Treasury bond with the same maturity. Therefore, the default risk premium on corporate bonds can be calculated as follows:Default risk premium on corporate bonds = Corporate bond yield - Risk-free bond yield= 7.15% - 3.1% - 1.3%= 2.75%The default risk premium on corporate bonds is 2.75%.Hence, the answer is: Default risk premium on corporate bonds is 2.75%.