Ruby is 25 and has a good job at a biotechnology company. She currently has $8,400 in an IRA, an important part of her retirement nest egg. She believes her IRA will grow at an annual rate of 7 percent, and she plans to leave it untouched until she retires at age 65. Ruby estimates that she will need $875,000 in her total retirement nest egg by the time she is 65 in order to have retirement income of $20,000 a year (she expects that Social Security will pay her an additional $15,000 a year).