You are considering buying an Audi for $50,000, and your financing is quoted at 7% APR with monthly compounding. a. What rate do you need in order to use one of the following annuity formulas to find the monthly payments? 1 1 PV(annuity of C for n periods with interest rate r) = Cx (mm) or PV(growing perpetuity) = r-g (1 + r)n b. What is the effective annual rate of interest for this financing? a. The rate that should be used for the formulas is r= (Round to six decimal places.) % b. The effective annual rate is (Round to four decimal places.)