Helen plans to invest some money so that she has $3,900 at the end of three years. Determine how much should she invest today given the following choices: (Do not round intermediate calculations and round your final answer to the nearest penny.) a. 4.2 percent compounded daily. Amount required to be invested $ b. 4.9 percent compounded monthly. Amount required to be invested $ C.5.2 percent compounded quarterly. Amount required to be invested $ d.5.4 percent compounded annually. Amount required to be invested $