Compound interest (a) You are to choose between two investments: one pays 6% compounded quarterly, and the other pays 5% compounded daily. If you plan to invest $20,000 for 2 years, which investment should you choose? How much extra interest will you earn by making the better choice? (b) At the end of 8 years I have $15,000. I invested in an account earning 4% annually compounded quarterly. How much money did I start with? (c) I invest $2000 at 10% compounded continuously. How long will it take for the account to be worth $3000?