It is Sarah's 21st birthday today and she has received an inheritance of $50,000 from her grandfather. Sarah will spend one-half of this inheritance, and use the rest to start a retirement savings fund. She plans to retire on her 67th birthday and she expects her retirement will last for twenty-five years. Sarah has set up a retirement savings fund that pays interest of 4.05 percent compounded monthly. When she retires, Sarah will transfer part of the proceeds of her retirement savings fund to a fund that will give her income payments of $4000 per month in advance during retire- ment. Her retirement income fund will pay interest of 312 percent compounded monthly. Sarah will use the rest of the proceeds of her retirement savings fund to set up a fund from which she plans to bequeath $500,000 to her grand- children on her 80th birthday. Her bequest fund will pay interest of 41?2 percent compounded annually. Calculate the amount of the monthly deposit Sarah must make into her retirement savings fund in order to fulfill her retirement income and bequest goals.