If $18,000 is invested at 11% compounded (a) annually. (b) semiannually, or (c) quarterly, what is the amount after 7 years? (a) If it is compounded annually, what is the amount after 7 years? A=$ (Round to the nearest cent as needed.) (b) If it is compounded semiannually, what is the amount after 7 years? A=S (Round to the nearest cent as needed.) (c) If it is compounded quarterly, what is the amount after 7 years? A=$ (Round to the nearest cent as needed.)