Investor I.M. Young has been investing $100 per month for the last 20 years making payments at the beginning of each month. I.M. Young plans to continue this investment practice for the next 20 years. Investor B. Tardy is just starting his savings program and plans to invest $400 per month for the next 20 years. B. Tardy's payments are made at the beginning of each month and at the same interest rate as I.M. Young. At the end of 20 years, Tardy's savings matches that of I.M. Young. Investor Rich Quick also begins his investment program today by investing 10,000 at the same interest rate. How many years are needed before Rich Quick has a savings of 90,000?