Frank has deposited $1 000 at the end of each year into a retirement savings plan for the last 10 years. His deposits earned interest at = 8% for the first 3 years, at =10.25% for the next 4 years, and at =9% for the last 3 years.

a) What is the accumulated value of his retirement plan? b) What is the total interest earned for the 10 years? c) Find an equivalent interest rate (same for 10 years), which conducts to the same results of a) and b).