In this paper,we suggest two methods to derive the expected value and the variance of the present value of some annuity immediate,and we find recursive relationships for the variance of the present value,and solve these relationships.
本文给出两种方法计算在某些年内一类延付年金的现值之和的期望和方差,获得了给付现值的方差的递推关系,并且解决了这些关系,这在计算简单方面明显地更好。