life annuity

Statement 3分两部分理解：

1. If Janice were to add a 10-year period certain option to her annuity, her income yield would be reduced when compared to not having the option,

如果一个人买了一个年金，但是同时他又买了个10-year period certain，那么就是即使他买完年没几年就死了，他依然可以拿到10年的年金。所以是增加了N，增加了N，则PMT下降，则yield income下降。

2. but it would be reduced by greater amounts the longer she waits to purchase the annuity.

后半句：

比如一个人30岁买annuity with 10-year period certain，她努力活到40岁对他没什么问题，所以30岁的时候买年annuity with 10-year period certain没什么意义，N不会被拉长

如果这人83岁买annuity with 10-year period certain，85岁就死，N原本=2，那么现在被拉长成了10，N上升，PMT下降。

这个statement的后半句想表达的是这个意思，确实不够清晰