(Compound value solving for n?) How many years will the following? take? a.?$ 520 to grow to ?$ 1,330.18 if invested at 11 percent compounded annually b.?$ 37 to grow to ?$ 73.72 if invested at 9 percent compounded annually c.?$ 115 to grow to ?$ 501.80 if invested at 12 percent compounded annually d.?$ 57 to grow to ?$ 69.35 if invested at 4 percent compounded annually