请问最后一个小题，求y预测值的标准差的公式需要掌握吗，课件中未找到该公式。谢谢

请问13，14题应该怎么思考啊？我不理解答案的思路

Benefit obligation和pension obligation什么区别啊

15题好像没有学习过这个知识点

请问14题为什么不是1000higher

请问，这页里为什么ln y可以写成delta y/y？

请问该如何理解notes中关于insurance company earnings的这段话？The underwriting loss ratio measures the relative efficiency of the company’s underwriting standards (whether the policies are priced appropriately relative to risks borne), while the expense ratio measures the efficiency of the company’s operations. underwriting loss ratio不包含underwriting项，却能衡量underwriting的质量；而expense ratio中包含underwriting expense，却是用来衡量公司operation的效率？

请问该如何理解notes中关于insurance company earnings的这段话？The underwriting loss ratio measures the relative efficiency of the company’s underwriting standards (whether the policies are priced appropriately relative to risks borne), while the expense ratio measures the efficiency of the company’s operations. underwriting loss ratio不包含underwriting项，却能衡量underwriting的质量；而expense ratio中包含underwriting expense，却是用来衡量公司operation的效率？

请问该如何理解notes中关于insurance company earnings的这段话？The underwriting loss ratio measures the relative efficiency of the company’s underwriting standards (whether the policies are priced appropriately relative to risks borne), while the expense ratio measures the efficiency of the company’s operations. underwriting loss ratio不包含underwriting项，却能衡量underwriting的质量；而expense ratio中包含underwriting expense，却是用来衡量公司operation的效率？

请问该如何理解notes中关于insurance company earnings的这段话：“The underwriting loss ratio measures the relative efficiency of the company’s underwriting standards (whether the policies are priced appropriately relative to risks borne), while the expense ratio measures the efficiency of the company’s operations.”？ 为何underwriting loss ratio中没有包含underwriting项，却能衡量underwriting的质量呢？而expense ratio中包含underwriting费用，却用来衡量公司经营效率呢？