① [(−3% − 5.4%)^2×0.1 + (3% − 5.4%)^2×0.3 + (7% − 5.4%)^2×0.4 + (10% − 5.4%)^2×0.2 ]^1/2
②[(2% − 9.4%)^2×0.1+ (4% − 9.4%)^2×0.3 + (10% − 9.4%)^2×0.4 + (20% − 9.4%)^2×0.2 ]^1/2
注：但望能体谅!