Bibi and Henry are celebrating the birth of their daughter, Fiona. They want Fiona to be able to attend college when Fiona turns 18. They estimate that the tuition expenses will amount to $25,000 per year for four years, with the first installment due exactly 18 years from now. Bibi and Henry want to deposit money now into an account paying 6% per year.

How much must they deposit now in order to fund Fionas college expenses?