Susan Robinson is planning for her retirement. She is 30 years old today and would like to have $600,000 when she turns 55. She estimates that she will be able to earn a 9.00% rate of return on her retirement investments. She wants to set aside a constant amount of money every three months to help achieve her objective. How much money must Robinson invest at the end of each of the next twenty-five years to realize her goal of $600,000 at the end of that time?