4) Nandana invests $500 at the start of each year for 20 years in a bank account paying interest at the effective annual rate i. She takes the interest paid at the end of each year and invests it in a different account paying an effective annual rate i/2. The effective annual rate she earns on her combined investments is 6%.

a) How much money does she have at the end of 20 years? (Total of both accounts.)

b) What is i?