4-20. Compound interest is a very powerful way to save for your retirement. Saving a little and giving it time to grow is often more effective than saving a lot over a short period of time. To illustrate this, suppose your goal is to save $1 million by the age of 65. This can be accomplished by socking away $5,010 per year starting at age 25 with a 7% annual interest rate. This goal can also be achieved by saving $24,393 per year starting at age 45. Show that these two plans will amount to $1 million by the age of 65. (4.7)