4-61. Suppose you are now 20 years old. You decide to save $A per year starting on your 21st birthday and continuing through your 60th birthday. At age 60 you will have saved an accumulated (compounded) amount of $F. A friend of yours waits five years to start her savings plan. It takes annual payments of $2A for her to accumulate $F when she becomes 60 years old. Still another friend delays his savings plan until 10 years after you started yours. He finds that it takes $4A each year until his 60th birthday to accumulate $F. What effective annual interest rate (i’) makes the above three savings plans equivalent? What message does your answer convey to you? (4.10)