请问我用0.65%和0.75%分别先乘以1/4，再分别带入（1+RFX）(1+RFC)-1计算，最后再加总，为什么不对？

NO.PZ202112010200003101 问题如下 Whis the approximate unheeexcess return to the Unitetates–basecret manager for internationcret portfolio inx equallyweighteacross the four portfolio choices, assuming no change to spreration anno changes to the expecteloss occur? A.–0.257% B.–0.850% C.0.750% A is correct. We solve for the excess sprebysubtracting ExpecteLoss fromthe respective OAS:Recall ththe UniteStates–baseinvestor mustconvert the euro return to US llars using R =(1 + RF(1 + RFX)– 1, so the USIG anUSHY positions comprising half the portfolio return average0.80%, while the EUR IG anEUR HY positionsreturn –1.314% in US llterms (= ((1 + ((0.65% + 0.75%)/2)) × 0.98) – 1), so –0.257% = ((0.80% – 1.314%)/2). 请问0.98怎么来的？

NO.PZ202112010200003101 问题如下 Whis the approximate unheeexcess return to the Unitetates–basecret manager for internationcret portfolio inx equallyweighteacross the four portfolio choices, assuming no change to spreration anno changes to the expecteloss occur? A.–0.257% B.–0.850% C.0.750% A is correct. We solve for the excess sprebysubtracting ExpecteLoss fromthe respective OAS:Recall ththe UniteStates–baseinvestor mustconvert the euro return to US llars using R =(1 + RF(1 + RFX)– 1, so the USIG anUSHY positions comprising half the portfolio return average0.80%, while the EUR IG anEUR HY positionsreturn –1.314% in US llterms (= ((1 + ((0.65% + 0.75%)/2)) × 0.98) – 1), so –0.257% = ((0.80% – 1.314%)/2). 在其他的问题回答中老师说“题目说了no fault loss occur”，但是题目说的是对于fault loss的expect没有改变，不考虑fault loss吗？如果考虑的话，是如何计算的呢？

NO.PZ202112010200003101 问题如下 Whis the approximate unheeexcess return to the Unitetates–basecret manager for internationcret portfolio inx equallyweighteacross the four portfolio choices, assuming no change to spreration anno changes to the expecteloss occur? A.–0.257% B.–0.850% C.0.750% A is correct. We solve for the excess sprebysubtracting ExpecteLoss fromthe respective OAS:Recall ththe UniteStates–baseinvestor mustconvert the euro return to US llars using R =(1 + RF(1 + RFX)– 1, so the USIG anUSHY positions comprising half the portfolio return average0.80%, while the EUR IG anEUR HY positionsreturn –1.314% in US llterms (= ((1 + ((0.65% + 0.75%)/2)) × 0.98) – 1), so –0.257% = ((0.80% – 1.314%)/2). 1-0.02 还是 1除以1.02

NO.PZ202112010200003101 问题如下 Whis the approximate unheeexcess return to the Unitetates–basecret manager for internationcret portfolio inx equallyweighteacross the four portfolio choices, assuming no change to spreauration anno fault losses occur? A.–0.257% B.–0.850% C.0.750% A is correct. We solve for the excess sprebysubtracting ExpecteLoss fromthe respective OAS:Recall ththe UniteStates–baseinvestor mustconvert the euro return to US llars using R =(1 + RF(1 + RFX)– 1, so the USIG anUSHY positions comprising half the portfolio return average0.80%, while the EUR IG anEUR HY positionsreturn –1.314% in US llterms (= ((1 + ((0.65% + 0.75%)/2)) × 0.98) – 1), so –0.257% = ((0.80% – 1.314%)/2). 公式里最后一项expecteloss，不是预期损失吗，和是否发生违约有关系吗？是否能需要计算最后一项