Units of $1 are deposited at the beginning of each year for n years into a financial instrument offering an interest rate of i annually. The interests are then re-invested into another financial instrument offering the interest rate of j annually. a. Derive the accumulated function of deposited fund at the end of n. years based on i and j above. b. At n = 10,i = 5% and j = 4%, calculate (a). c. If j = i, show that (a) is equal to the future value of annuity - due at interest rate of i.